Mobile phones

Mobile phones can be an excellent tool for keeping in touch while travelling. Given advancements in technology, in addition to providing phone service they also act as tools to capture and share moments from your trips as well as help you find information about places whilst on the move, and book and pay a variety of travel services.

Mobile phone basics

The main ways you can use a cell phone while travelling overseas include:

Taking your phone and SIM card (or eSIM), and use the foreign network through agreements between the two operators (roaming)
Purchasing a SIM card at your destination, and installing it in place of or in addition to your home SIM card
Purchasing an eSIM before or during your trip, using it like a purchased physical local SIM
Renting or purchasing a phone and SIM card at your destination
Renting or purchasing an international cell phone and SIM card prior to departure

The SIM card determines your phone number. Some phone models allow your using two SIM cards in parallel, which should always be possible with eSIMs. If not, you can have your old SIM in one phone and the local SIM in another. Depending on intended usage, either may be a cheap one brought from home or one bought locally. In some regions, you may want to use a cheap phone bundled with a local SIM.

Roaming with your existing phone and SIM card may be manageable when visiting one European Union country from another, but further abroad (even in countries that neighbour the EU) the cost may be prohibitive or the service not available. Pre-paid SIM cards are cheap and easily available in some countries, where there may be severe restrictions in other countries.

In some countries, there are multiple political entities, such as in a federal state like Mexico, or such as Hong Kong and Macau versus mainland China. In these cases you might need to activate roaming to get your SIM to work across the border. Roaming in Åland with a Finnish SIM you pay the same price, but in Mexico or these Chinese territories, you pay additional roaming fees – which may be very expensive. If you buy a local SIM-card, make sure it is possible to use it without roaming (or with free roaming) in all places you are going to visit. Even without the roaming problem, your provider may not serve all the country, or just the biggest cities in part of it.

Usage

See also: Smartphone apps for travellers

You should be able to use your smartphone as at home, with caveats of compatibility, network coverage and costs, discussed below. In addition to your standard apps, there are many smartphone apps especially useful for travelers.

Most mobile phones come with a camera, and are useful for travel photography and video recording. These are usually less capable than a good dedicated camera, but they offer the advantage of portability as they are small and inconspicuous, as well as integration with other useful apps.

For video recording or if taking lots of photos, your memory card may run out of space, and it is easy to lose the minuscule modern ones while changing cards in busy areas or off-road. Plan ahead so that you can do it in a comfortable environment, or perhaps offload to USB sticks (using a laptop or a suitable adapter), which are easier to handle. Mobile data can be used to upload the recordings, but do your math on storage needs, expenses and upload times with realistic (or worst-case) bandwidth.

Calls over Internet

Smartphones may be able to place voice-over-IP calls using a wireless Internet hotspot (or, with the right software, any decent Internet connection) by installing a softphone application and signing up to a VoIP provider. This is an inexpensive way to talk, avoiding fees for roaming or international calls – unless your Internet connection is expensive. When calling someone who's also using an Internet phone or app connected to the same servers, using a free Wi-Fi hotspot, the calls may even be free.

Some mobile phone providers offer to use the internet, either a local Wi-Fi or their own mobile data, for any calls, where 4G or Wi-Fi is available. They might charge as for normal calls also for these. If they charge as for local calls (+ roaming data?), this may still be cheaper than the normal rate for roaming calls.

VoIP calls are independent of the local telephone networks, but are limited by the availability of Internet connectivity, and sometimes blocked at the Internet firewall. If your Internet connection is by mobile data, these VoIP calls can be anything from free to expensive, depending on your mobile phone provider. In addition to voice they may offer video, text chat and file transfer connections to compatible applications.

Internet voice providers tend to fall into three categories: Some are generic Voice-over-IP gateways which follow an Internet standard (SIP) and allow calls to regular phone lines from users of any application that follows the standard – often for as little as a penny or two per minute, with no minimums (many small independents fall into this category; in the US, Google Voice may be another option). Others are proprietary apps (such as WhatsApp, Viber, Line, Skype, Facebook Messenger or WeChat), foremost connecting users of the same service, with calls to other systems usually treated as calls to the switched telephone network. The apps are downloadable from the app store for your phone operating system, most often for free. The third group caters to non-travellers, offering their own desktop VoIP phone to connect to your regular internet connection.

Bring your phone

Handset with slots for two SIMs (and a microSD), allowing using both a domestic and a local number without swapping SIMs

The beautiful thing about standards is that there are so many to choose from. There is a vast selection of mobile networks and handsets that not only aren't on the same wavelength, but aren't even speaking the same digital language. Fortunately, if you have a smartphone purchased in the last couple of years, the chances that it will work internationally have improved slightly. Nonetheless, it's worth checking the compatibility before you leave.

One caveat about bringing your phone is that it may contain valuable information that you don't want to lose, or that shouldn't get into the wrong hands (including any info available through your apps, such as social media accounts and conversations). See Business travel#Data security for a discussion. Some might prefer to carry a separate phone, with only reasonably insensitive data (and perhaps a cheaper model). You could transfer your SIM to it, checking what data you have on it (your address book?) and backing it up as appropriate.

There are various "generations" of mobile telephone, which contain multiple, sometimes-incompatible standards. Each generation represents around 10 years in mobile phone technology:

1G was analogue mobile phone services, such as NMT and AMPS. Shut off circa 2008; now dead.
2G is the first batch of digital mobile phones. 2G networks are now an endangered species, and most of the few remaining ones are scheduled to be shut down to free up bandwidth for 5G. You might want to disable 2G on your phone, as some security issues can be exploited by having the phone fall back to 2G. There are at least three standards which do not interoperate at all:
- GSM was the most widely used mobile phone standard in the world, originating in Europe in 1991. GSM has been made largely obsolete by 3G and 4G; many telcos have shut down their GSM networks, and more will do so through 2024. Some are keeping this network as backup for those whose phones lack proper 4G support, shutting down 3G instead.
- CDMA (more specifically cdmaOne) originated in the United States in 1995, and was mainly used in the U.S., Canada, South Korea and China. Some major providers opted for CDMA and others opted for GSM in the U.S., Canada and China, while CDMA was the only 2G standard adopted in South Korea. The U.S., Canada and South Korea have all shut down their last 2G CDMA networks, while China Telecom still reserves one for devices that fail to access 4G VoLTE to make phone calls.
- PDC was a standard that was exclusive to Japan, and also the most widely used 2G standard used in the country. This unique standard meant that foreign mobile phones could not be used in Japan and vice versa. The last network was shut down in 2012.
3G was an advancement that was similarly split into two formats.
- Most networks used UMTS or its variants, an evolution of GSM. W-CDMA is the original version of UMTS; HSPA/HSPDA and HSPA+ are UMTS upgraded for faster Internet data downloads. UMTS was also adopted as the 3G standard by some Japanese and South Korean carriers, making it possible for people from GSM-only countries to roam to Japan and South Korea for the first time. UMTS networks are being shut down to free up bandwidth to expand LTE and 5G networks; several carriers have already switched off UMTS networks, with many more expected to do so through 2028.
- Just like 2G, a minority of networks used CDMA2000 (specifically EV-DO), an evolution of CDMA. Many of these had shut down by 2020 and the trend continues.
- As the concept of a "generation" of mobile handsets is largely defined by marketers, some advertised CDMA2000 1X (a faster CDMA) or EDGE (a faster GSM) as "third generation", "3G" or "3x". These standards are not UMTS or EV-DO; the respective incompatibility issues of GSM vs. CDMA all remain in EDGE and EV-DO.
- The same blurred boundaries between "generations" exist with HSPA+ (a faster 3G UMTS branded occasionally as 3.5G or 4G).
- Modern smartphones entered the market in the latter half of the 3G era. Unless you have a very early-model smartphone (e.g. the first-generation iPhone), there is a very good chance your smartphone is at least 3G-capable.
4G is a faster data connection available in major cities and possibly elsewhere, supported by most modern smartphones. Frequency bands vary by region; some handsets support half a dozen options. As of 2017, all 4G handsets also support 3G standards; most handsets can also fall back to GSM if the network supports it. Old 4G phones do not necessarily support voice over 4G, so they depend on a working 2G or 3G connection for voice calls. However, some providers are phasing out 3G, which means you may have to fall back to 2G or are out of luck.
- LTE, also known as FD-LTE or LTE-FDD is the main international 4G standard. It was designed as a unified international standard to succeed both UMTS and CDMA2000, meaning that most carriers around the world, regardless of what 2G or 3G standard they used, have adopted it for 4G.
- TD-LTE, also knowns as LTE-TDD is also 4G but not compatible with standard LTE. It is mainly used in China, where is it is the most widely used standard. However, as some countries outside China have started adopting it, more device manufacturers have started including support for it. China also has standard LTE, though its coverage is not as good as TD-LTE.
- WiMax was a standard used by Sprint in the US and UQ in Japan, and now fully decommissioned.
5G networks have been rolling out to certain locations since 2019. Many countries have 5G networks available now in major cities, although phones with "global" 5G support are not widely available yet. 5G is not intended to replace 4G, but gives faster data in cities (it relies on short distances to base stations). It is controversial security-wise, as manufacturers (and perhaps others) can update the network devices stealthily without authorisation from operators, to eavesdrop or to do other nastiness.

There are also multiple frequencies. A handset which lacks the local frequencies or does not use a compatible standard will not connect to the network. Again, the more modern your phone the more likely it is to work across frequencies.

Outside the Americas:

900 MHz and 1800 MHz are the most common GSM frequencies
900 MHz and 2100 MHz are the most common 3G (UMTS) frequencies
In Australia, 1800 MHz used for 4G. 850 MHz provides good 3G UMTS (Telstra) coverage.

In the Americas (ITU zone 2):

850 MHz and 1900 MHz, the most common GSM or CDMA frequencies, are used for 3G (UMTS) on AT&T and all Canadian major carriers (Bell, Rogers, Telus)
1700 MHz and 2100 MHz are used for 3G (UMTS) on the US T-Mobile network
1700 MHz was used for Canadian new entrants, regional carriers (Eastlink, Vidéotron) and 4G (LTE) services.
Additional bands (such as 2600 MHz) may be used for 4G LTE to carry high-speed data

If your phone matches all frequencies of the telco network in the country you are travelling to, it should receive a good signal when roaming or with a local SIM card. If your phone only matches one of the frequencies, it may only work in some locations.

The last thing to check is the SIM (subscriber identity module), a small card which assigns a carrier and telephone number to a handset. There are two options for using your existing handset abroad:

Roaming leaves your existing SIM and carrier in place, relying on agreements between your home carrier and a carrier at your destination to route calls using your existing mobile telephone number. This gets expensive, as billing goes through two telephone companies; any calls to you have to go to your home country first, then back out internationally, further inflating cost. This may be a viable option if visiting one European Union country from elsewhere within the EU, as regulators have implemented new "roam like at home" rules allowing part or all of one's plan allowance to be used anywhere in the EU at no extra cost. Elsewhere, it can be costly and normally will not be permitted at all on prepaid cash mobile plans. In some cases there may even be roaming surcharges without crossing national boundaries. This is especially true in countries with weak regulations or where one or a handful of companies have "cornered" the market; regional carrier handsets may "roam" when taken to domestic locations outside a limited home region.
Obtaining a local SIM allows the traveller to obtain a local prepaid plan with a local mobile telephone number at local prices. This won't work if a handset has been locked to only accept one provider, although codes to unlock many common handsets may be purchased from third-party sites online.

Some handsets are made specifically for use with two different SIMs. These are known as "dual SIM" as they have two card slots, where the SIMs can be from different mobile operators. This allows having your private and work number on the same phone or, for travellers, to have SIMs from different countries. The capabilities of such devices vary; some are effectively two-line phones on which each virtual line subscribed to a different number, with others you have to manually switch from one SIM to the other, you might even have to power off and on to do that. With the former models you will be able to receive calls and text messages on both numbers, while you can choose which SIM to use for data and outgoing calls and messages. You probably want to use the local SIM most of the time, but for calls from home (or otherwise from abroad) you might want to answer them directly, call back using the local SIM or call back using your home number, depending on the options' costs. Similarly with messages. With the latter models you can check missed calls (if your operator tells about them) and received messages on your home number when you feel like, while using the local SIM otherwise. If your home operator doesn't have a local roaming agreement, you will be out of signal with your home number, but can use the local SIM as usual.

You can get similar benefits from having a second phone with the local SIM. In some places cheap simple phones (perhaps locked to a local SIM), or relatively cheap advanced phones you want to bring hone, are widely available.

Due to upgrades, many travellers have old handsets which are still functional. If this has the local frequencies, bring it; one handset keeps your existing home number active while the other takes advantage of reduced costs with a local SIM card. If a call arrives for your main number, call back from the local SIM at local prices instead of paying the higher fee for roaming. In areas with thieves, you may also want to avoid flashing your latest model phone.

If you are travelling with an older phone, you may have more issues with compatibility than with modern ones. This is emphasized when 3G networks are being shut down.

Carrying a phone which isn't compatible with local networks may still be useful: for map reading, photography, museum audio guides, and web browsing via local Wi-Fi – or Wi-Fi shared from your hidden main phone. If a thief snags the phone while you are studying the map, you'll prefer that they take your secondary phone, preferably without much private information.

Roaming

Using your phone in places other than its home area is called roaming. if you intend roaming, you should do your homework before you travel. You need to understand the price and what is included. If you're roaming the cost may be no different to home (e.g. most EU-based subscriber roaming within the EU), you may be able to pay a fixed fee per day, or the cost can be thousands of dollars for only moderate usage – depending on your carrier, contract and destination. You can pay to make calls, to collect voicemail, and even if someone calls you and is diverted to voicemail. Background data can accrue costs from the second you turn your phone on.

Consider using text messaging (SMS) as a cheaper alternative to making per-minute phone calls. These text messages can be sent between phones, with up to 160 bytes per message (messages can nowadays be longer but are still delivered and paid for in such chunks). While SMS messages can be more expensive when overseas (from US$0.30 to 1.00 each), they are cheaper than international calls and can be very useful for keeping costs down. Sometimes receiving them can be free. Moreover, those who send you an SMS using a carrier back home will be charged at local rates.

There are two things you have to check to ensure that roaming will work when you arrive:

Is your phone the correct type and can it communicate on the frequencies required by the foreign network?
Does your home carrier have roaming agreements with at least one carrier in the country you are visiting,
Are you on a plan permitted to roam to another country or have you purchased a bundle that allows you to do so?

Your phone

While roaming on your existing carrier lets you bring your home number with you, your phone must support the standards and frequencies of a network at your destination with which your carrier has a roaming agreement.

There is no need to unlock the handset or replace the SIM card, but if you're on the wrong frequencies or carry a CDMA-only handset into a country whose providers only support GSM, you will have no signal. Your home carrier should be able to tell you what networks are supported on your handset and plan.

Your carrier

Your carrier must have an agreement with a carrier at your destination to allow you to roam. Check that an agreement is in place and what frequencies the roaming carrier uses against the capabilities of your phone.

Official EU roaming information page – for EU related information (tariffs, hints). Although in most cases EU usage supposed is billed against a subscriber's allowance, some exceptions apply, especially for providers that offer mobile data for bargain basement rates. In addition, some providers may only open their "roam at home" scheme to those who have established "stable links" to their home EU country.

Check that your plan allows international roaming. It may need to be enabled, which is much easier to accomplish before you leave home. Many pre-paid plans do not permit any form of international roaming, limit the networks that you can roam to or limit enabled services (such as SMS only). You may need to purchase an international roaming package from your home provider - if not using an alternative, this is much cheaper than paying it "ala-carte".

Most phones default to a setting which automatically chooses a network for roaming. When in areas near the border of your home country or intended destination, it may be worthwhile to change the setting to manual, and to keep to your home network until you lose the signal. The farther away from the border, the weaker your home carrier's signal; depending on terrain you might lose the signal already before the border, and likely at latest 5 mi (8 km) beyond it – but you avoid your phone picking up an expensive network across the border when your domestic one still works or when you don't need to be connected.

The foreign signal may actually be stronger also without crossing the border, especially in mountainous terrain, where the domestic signal is unreliable, where the signal path to the foreign tower is directly across water, and in backcountry, where no domestic towers are near. Mobile users in border regions like Niagara Falls, Windsor–Detroit or the Thousand Islands often disable roaming from the phone's menus to avoid being randomly hit with roaming charges on mobile telephones which never left their home country.

Rip-off networks

There are an increasing number of localized nano networks (especially in Europe) that may, unbeknownst to you, "capture" your mobile if you have set it to "automatic" network selection. For example, if you are travelling on a Stena line ferry the few miles between Scotland and Northern Ireland, the strongest signal is likely to be their own network with roaming charges of more than €1.50/min for incoming calls rather than the €0.05/min that the call would be capped at if you were still using an EU network. Cinemas have now got in on the act and are abusing what was once a socially useful technical advancement to stop phones ringing during performances.

At sea or in the air, out of contact with normal carriers, a ship or jet's local network connected by satellite may truly be a service for those needing it, but the prices may be outrageous for those who could get by without – or when automatically switched to when land-based networks are still in reach (even in the harbour or airport).

Local SIM cards

A SIM is a card which is inserted into an UMTS or GSM handset (in older phones often under the battery). It is necessary on GSM phones, where it provides the handset's identity as seen by the network. In CDMA handsets the functionality was integrated, but most now accept SIMs (or the R-UIM or CSIM variety). Local SIM cards are often a much cheaper alternative to roaming.

There are 2 major types of payment scheme: pre-paid contract (sometimes known as "pay as you go") vs subscription contract (paid on each consecutive month, post-paid).

While a local SIM is usually much cheaper for local calls than roaming, other considerations may apply for calls from or to abroad, such as to friends at home. You have four options, the fees of which may differ significantly:

having them call your normal number (you pay a roaming surcharge)
your calling them with your normal number (you pay for an outgoing international call, plus the roaming surcharge)
having them call your local number (they pay for an international call)
your calling them with your local number (you pay for an outgoing international call).

With a local SIM, the phone – unless locked to the original carrier – is treated like a domestic one, with a local telephone number. Some prepaid cards include a small amount of prepaid airtime (typically no more than half the face value of the card, sometimes even more than it). The value of the airtime of course depends on call and data fees, which may differ from those typical on non-prepaid subscriptions, or between companies.

Prepaid SIM cards may work without account setup, credit card numbers or bank accounts or they may require registration (to reduce use of phones by criminals), either at purchase time or before usage. If registration is needed, you may want to get the SIM working before you leave the shop, to let the clerk solve any problems. In a handful of countries, purchase of SIMs by non-residents comes with some form of restrictions.

To add credit to these SIM cards, buy "refill" (the common term in the US), "top up" (Singapore, the UK, Canada and New Zealand), "recharge" (Hong Kong and Australia), "reload" (Philippines) or "add value" cards or vouchers from news stands, telephone stores or convenience stores. ATM or online credit card top-ups may be possible with some providers; however doing so through their websites may require the user to have a domestic debit/credit card or bank account. In some countries, credit (prepaid or plan) may be transferred between users of the same network by sending an SMS to the provider.

In some large international airports, outside security, mobile phone shops will offer a prepaid SIM without leaving the airport. A few vendors offer SIM cards intended specifically for visitors.

A SIM card showing instructions for breaking it into various sizes as required by different models of phones

As a prepaid product, the SIM card and the credits have limited lifespans. Unless periodically reloaded (usually with a code purchased from a local store or on a website with a local credit card) the SIM and the local telephone number will expire. As a general rule, lower top-up denominations tend to expire more quickly.

The card is packaged as a credit card-sized piece of plastic from which you can break out a smaller chip card in one of three sizes (mini SIM, micro SIM, nano SIM). The chip is the same, there's just less plastic frame around a SIM in the micro and nano size versions used by some phone models (the original SIM was credit-card sized). Some very old phones may require a mini SIM a little thicker than those including nano versions, check if relevant for you .

A local SIM means one more number that you need to inform important contacts about; if you intend to visit many countries it may be easier to obtain a service which can be call-forwarded cheaply (such as a Voice-over-IP provider), distribute that number to your contacts and forward its calls to your local mobile phone/SIM when you enter a new country.

While voice calls should work as soon as you install a subscribed SIM card and re-apply power to the handset, data may require various settings to be configured so that the handset can find the Internet gateway. Usually the set-up is automatic using configuration data on the SIM card, but sometimes it has to be done manually via setting provider-specific Access Point Name (APN) settings.

If you are buying a SIM card, it may be worthwhile purchasing from a telco outlet so your phone can be working before you leave. This will save any confusion with having to apply settings yourself. Otherwise you may have to check the providers website, which can be difficult if you don't have mobile data configured. A few providers may also supply a username and password for mobile data. Carrier technical support is usually limited to providing a list of settings and advising you to ask your handset manufacturer. While MMS might only be needed for a specific few applications (usually, sending photos by text message), if you leave out the access point name (APN) you have no mobile data. Handsets purchased from individual providers usually preload the settings for that provider, but if you bring your own unlocked handset, you need to add your local SIM provider to the connection list for data. There may also be a setting to point the mobile browser to the new connection on the list, instead of your home carrier's gateway.

If your handset gives one-button access to voicemail, there is a number (listed in the configuration menu) which is auto-dialled by that feature. This number usually is read from the local SIM, but it's best to verify. Any on-screen "message waiting" indicators will only work for the currently-installed SIM, even if messages are waiting on your home provider (original SIM) and local provider (local SIM). Some handsets also use memory space on the SIM to store phonebook entries or Wi-Fi passwords; swap SIM cards and you may need to copy or re-enter this data.

International SIM cards

An international SIM card is a SIM card meant for roaming in several countries. They are generally more expensive than local SIMs, but free you from the need to buy a new SIM in every new country (and deal with real name registration requirements), with unused airtime left on the old one. Thus they may be an interesting option if you are visiting several countries in a short time frame (EU is an exception, as there a SIM bought in one country should work in all of them).

The "international" cards usually allow free or cheap incoming calls in a significant number of countries and offer relatively cheap outgoing calls via an automatic callback service. This avoids multiple changes of numbers.

In general, there are many companies that just re-sell services from several big roaming providers. More than half of all international roaming SIM cards are based on just three platforms:

an Estonian platform with TravelSim, AirBalticCard and others (based on Top Connect OÜ);
a Jersey-based platform on JT Telecom with an "UK" number, that is in fact from Jersey;
on the Naka platform based on this MVNE from Switzerland

There are many different reseller companies available, so shop around – the prices can differ quite drastically. The cards sold at airports may not be the cheapest. A list and comparison of such services can be found on a specialized Wikia.

eSIM technology

eSIMs, or embedded SIMs, act like SIM cards, however instead of installing a physical SIM card, you install an app that configures your phone's hardware to manage the relevant mobile network connections. Increasing numbers of phones accept eSIMs in addition to physical SIMs. Notably, most iPhone models from the X series and newer support this technology. This allows you to operate multiple phone and data plans in your phone, which is great for travelers. It also means that you can actually purchase an eSIM before your trip and activate it the moment you step off the plane. Even though you can buy them long in advance, the eSIM does not get used until you activate it. This also avoids the hassle of going to a SIM shop, buying a SIM, and worrying about losing your home SIM as it swims around your bag for the duration of your trip. You can thus switch back to your home country's SIM card using the phone settings quickly if you are expecting an important SMS.

Airalo, Nomad, CMLink Global by China Mobile HK, and GoMoWorld are examples of companies that offer eSIMs for over 200 countries, usually giving the customer various options such as amount of included data and the length of time for which the eSIM will be active. Additionally, these companies offer some regional packages, whereby you can buy a single eSIM which will give you network access throughout Europe, Asia, or other regions. The eSIM is increasingly offered by many national providers although this does not do away with the real name registration requirements. Some eSIM providers also offer flight roaming.

The main downside is that an eSIM is not easily transferrable between devices – those that allow transfer may require you to contact the eSIM provider for assistance. Other downsides include that not all phones, particularly cheaper or older models, support eSIM technology. Some phones don't allow installing eSIMs from certain other carriers, even if unlocked. Do your research before purchasing. For the security conscious, the thought of having a remote-programmable chip in charge of your data connection may be unpalatable. However, there is a security advantage to eSIMs too: if your phone is stolen, the eSIM cannot be removed by the thief, which gives you a better chance of tracking and possibly retrieving your phone. Another downside is that they are often only data-only (except the ones by mainstream telecom providers).

It is also worth noting that certain phone models that feature eSIM functionality in one country may not feature it in another. This is the case for instance for phones in mainland China and Hong Kong. Therefore, if you want to buy a phone that is eSIM capable whilst abroad, make sure to check out first whether the manufacturer-in-question offers eSIM capability for that same model in the country you intend to buy it in.

Finally, note that some eSIM providers provide a promotional free period (which would normally be enough), usually through your credit card (and in addition discounts). Examples include Flexiroam and GigSky. Note that not all credit cards work (often determined by status and region), and there will usually be restrictions on how often you can make use of the free offer (eg once per year). GigSky in addition offers a 100 MB plan valid for one region/country that is open to all and does not require a credit card - however: it can only be used once per account so 100 MB region is better than 100 MB for one country, where applicable.

Locked and unlocked phones

If you want to use your own phone, you have to check (see above) that the phone can be used at your destination, type and communication frequencies and that it is unlocked (or "carrier SIM-locked".)

In some countries, providers may be required to provide subscribers with the unlock code for devices they own after a certain time period, usually for a fee. For many (but not all) common handsets, an "unlock" code may be purchased more cheaply from a wide selection of Internet vendors (typically US$10–20); more rarely a handset must be taken to a specialized vendor to be unlocked.

In Canada, beginning Dec 2017, cellphone customers can ask their provider to unlock their phones free of charge, and all newly purchased mobile devices must be provided to customers unlocked.

Unlocking a phone (to allow access to competing mobile carriers) is not the same as "jailbreaking" (which allow access to non-Apple software downloads on Apple devices) or "rooting" (which provides a "run as administrator" option for Android programs). Some phones are easier to unlock than others. Older Nokia phones can be unlocked at home with a simple code, while Motorola or Sony phones require additional equipment and may require you to bring your phone to someone. Some (Japanese domestic market phones) may use a different SIM-based method that attaches to your SIM, allowing you to take it from phone to phone. Shop around: unlocking services are generally cheaper and more easily available in Europe and Asia than in North America.

An alternative is to buy an unlocked phone. In some countries – for example China – phones are never locked. Various web sites and some shops in Western countries sell unlocked phones, usually at somewhat higher prices than the "deals" you can get by signing a contract for a service and taking a locked phone. Travel-specific capabilities like "quad-band", "dual SIM" or travel chargers, intended to keep handsets working on multiple carriers in multiple countries, are more likely to be available on factory-unlocked handsets from third-party electronics vendors. An unlocked 3G (UMTS/WCDMA) dual-SIM quad-band Android handset with no carrier-specific branding may cost anywhere from US$150 to 500 from an online mail-order house, depending on brand name and capabilities.

Renting or purchasing a phone abroad

You might want to use a separate phone to use with a local SIM, because your phone does not support the local network, because you want to continue to use your domestic number, or because you want to use a cheaper phone on the road. If you buy that phone before departure, you should check its compatibility, if you plan to buy it after arrival, check where they can be bought and plan for getting along until you have it.

You can often rent a local mobile phone, often even at the airport on arrival. However, in many countries purchasing a cheap phone and a pre-paid SIM will be more economical (even if used for just a week) as airport rental companies often charge much more per-minute than the local prepaid rates. Airport rental kiosks might be closed to travellers arriving on late night flights and may run out of phones during popular events in high travel season.

In some destinations, providers market artificially cheap prepaid handsets (in the US, "AT&T GoPhone" handsets start at $20 when the SIM alone is $10) but SIM-lock the handset to one provider which charges full price for the prepaid minutes. Unless the phone can be unlocked, it will not be usable with another carrier's SIM card on your return and should be treated as disposable. If you are going to other countries, you might want to buy an unlocked phone separately.

Especially in low-income countries or areas were theft and other types of crime are common, a major advantage of getting a cheap "disposable" pre-paid phone is that even if your phone is stolen you lose only the (relatively low) value of your phone and the remaining balance on the chip – and messages, call history and whatever else you stored on it – not the several hundred euro a new model smart phone might have cost you.

But if you intend to use a local phone and call local numbers, you might want to familiarize yourself with the local system and rates. In some countries those are not self-explanatory, and you may find your balance "disappearing" after just a few days of not calling anybody or other shenanigans played on you by a dominant company, especially in countries with weak or no government regulations to prohibit such business practices.

You might also check the procedure to activate your newly purchased phone: some models require you to register, accept terms and download updates, for which you may need or want working Wi-Fi, which may not be available where you buy the phone, or even at your lodging. If the phone is set to use a local language by default, you might need help to change language settings.

Renting or purchasing a phone before departure

By having your phone and SIM (or eSIM) before you go, you will have your phone number to give out to family, friends and co-workers. You will have a phone that is ready to use as soon as you land. Your handset will come with complete operating instructions in your language, with information on how to check the remaining prepaid credit balance, how to add additional credit, how to contact customer service, and how to make and receive international calls.

This of course requires that you can get a compatible phone and SIM at home. These are not necessarily sold in the local shops, and may in any case be more expensive than they would be at the destination. In some countries these can be relatively easy to find; for example Hong Kong has entire street markets dedicated to phones and SIMs of all types, for use both at home and abroad. Otherwise, Amazon has a decent selection of "globally compatible" phones that support the most common 2G, 3G, and 4G frequencies used around the world, as well as ready-to-use local SIMs for some countries. Also eBay is a good place to look for these, once you've done your homework and know what you're looking for.

Satellite phones

Inmarsat satellite telephone deployed after the 2005 Sumatra earthquake in Indonesia

In remote locations, without cell phone coverage, a satellite phone may be your only option. A satellite phone is not generally a replacement for a cellular phone; they're bulkier and have noticeably more delay than cellular phones, and you have to be outdoors with clear line of sight to the satellite to make a phone call. Satellite phone services are frequently used by maritime transport (including pleasure craft) as well as expeditions who have remote data and voice needs. Your local telephone service provider should be able to give more information about connecting to this service. Technology is changing all the time, with new and better services appearing regularly, particularly for internet connectivity.

Several networks use geostationary satellites, which can cover large portions of the Earth with as little as one satellite, and near global coverage with only a handful. In addition to voice calls, these can also provide relatively high bandwidth data connections (perhaps around 60 to 512 kbit/s, and up to 50 Mbit/s in some of the newest hardware). Such a system does have disadvantages: there's some delay (around 0.25 seconds, due to the speed of light), and it can be difficult to get line of sight if there are hills or trees in the way. They also cannot provide coverage at latitudes above 70–80 degrees. While the services are packaged and provided to consumers by a number of companies, it's more useful to describe the few satellite operators themselves. They are:

Inmarsat — Global coverage from 13 satellites
MSAT — North America
Terrestar — North America
Thuraya — Their network, using a Thuraya handset, allows roaming from GSM to satellite depending on network availability. Check to see if they have an agreement with your home network. Some networks (for example Vodafone UK) charge a very high rate for incoming calls (£6.00/min). If a lot of calls are to be made, buy a SIM card from a satellite phone provider. A Tburaya handset will accept a SIM from a regular mobile network if a roaming agreement is in place. Calls on the Thuraya system cost from $0.50–$1.30/min for their own SIMs. Thuraya uses geostationary satellites over the longitude of Europe, Africa, Asia and the Middle East, so check for coverage in the area you are travelling to. You may have to orient the antenna of the device towards the satellite for best reception.

Three other networks operate satellites in low Earth Orbit. These orbit the Earth every 1½–2 hours using a network of several dozen satellites. Reception on the ground changes rapidly over time, as each satellite is only in view for 5–15 minutes; as they arc across the sky, your signal may be temporarily blocked by obstacles. The network should pass connections to the next satellite, but if your signal is blocked before this can happen it can cause calls to drop. Data speeds are significantly lower at just 2,200–9,600 bit/s, although upgrades will bring this into the range of 128 kbit/s or better.

Globalstar — Globalstar's system is, in theory, capable of covering across most of the continents (but not the polar regions) and some of the oceans, but satellites relay calls directly to ground stations and there are gaps in certain remote areas where there are no nearby stations. Cost is typically $1–1.50/minute plus a monthly subscription; in most countries, Globalstar issues numbers which look to be within the country (so a Canadian might get a Calgary or Smiths Falls geographic number) and its subscribers pay to receive calls.
Iridium — The only truly global network, Iridium works anywhere with line-of-sight with the sky. Their satellites orbit pole-to-pole, ensuring coverage of every continent and ocean as well as excellent coverage in extreme northern and southern latitudes. Because calls are routed from satellite to satellite until they reach one of the four ground stations, delay is large and fairly variable (around 1 second up to 1.8 seconds). Expect to pay about US$1.50–2.00/minute for outgoing calls, with only slightly lower rates to call another Iridium phone. Iridium does not sell direct and only sells phones through dealers who may also rent units as well.
Starlink appeared in the 2020s; it uses a large number of low-Earth orbit satellites to provide fast internet connections in latitudes below 60°, and some high-latitude areas. Costs vary from place to place and are sometimes reduced by special offers, but generally around $500 to buy the equipment then $100 a month for the service. For prioritised customers (with fixed address) capacity is about 50–150 Mbit/s, with higher bandwidth offered for a higher price, mainly to business customers. For travellers to busy areas, availability may be greatly reduced, as locals are prioritised.

For fixed installations in off-the-grid locations, satellite Internet may be adequate to allow Internet telephony. This is a standard way to reach points like Chicken, Alaska or an outfitter's camp in the distant wilds of Labrador; as no local infrastructure exists, a business offering a Wi-Fi hotspot by necessity feeds directly to a dish.

Satellite phones may be unavailable for purchase or illegal in Saudi Arabia, India, Myanmar (formerly Burma), Cuba, Iran, Libya, North Korea, North Sri Lanka, and Syria. They will still function in these areas, however. Some countries require a special permit for using satellite phones within their territory.

Conversely, the Newfoundland government will lend a satellite phone with very limited capability to travellers on the Trans-Labrador Highway through remote regions of Labrador, where this is the only viable means to call for roadside assistance.

With long delays, you need to adapt your talking style: say one thing at a time, then wait for the answer, and keep silent while the other end is talking. Any attempt at "real-time" feedback reaches the other end too late to come in the right context. You might have seen such conversations on the news: the reporter on-site still listening a moment after each question. Not all internet telephony apps cope with the delays; they might think the packets have just been lost.

Purchasing a USB charger

A typical USB-C charger. Note that not all chargers provide the same support for features such as fast charging, which could affect some devices with high power consumption. Although sold as a package, the cable and charger can be swapped independently if physically separate like here.

Mobile device makers, in response to EU pressure, have been migrating to +5V USB as a standard connection for recharging handsets. It should be relatively easy to find a USB charger compatible with local electrical systems at your destination, or recharge from your laptop or any local computer. You will still need the cable connecting your phone to the USB contact on the charger. These are not fully standardized:

The former de facto Android standard of microUSB is now found only in older phones and a few low-priced models.
Apple devices have moved to USB-C, with recent phones and older iPads using the Lightning connector. Among iPhones, the iPhone 15 series, introduced in September 2023, is the first to use USB-C instead of Lightning.
Most non-Apple phones, as well as newer Apple tablets (specifically post-2018 iPad Pros, post-2020 iPad Airs, and post-2022 iPads), have migrated to USB-C, whose connectors are not compatible with earlier USB iterations. Starting December 28, 2024, all new phones sold in the EU must support USB-C (which led Apple to migrate the iPhone to that standard).

Some chargers have the cable inseparable from the charger. This offers less flexibility. If there is a standard USB outlet on the charger, and the corresponding standard connector on that end of your independent cable, you can continue using your cable with the new charger you buy across the border – and so can your friend, with their own cable. When you buy the new charger, you just have to check it has the USB outlet, you don't have to buy one that has the right cable. If it has, all the better, now you have a spare.

Information by region

Please see the Contact section of the destination country article for information on communications specific to one country.

Africa

Egypt will now let tourists buy SIMs, although the system to register foreigners is somewhat convoluted. It's recommended to do so at the airport on arrival instead of trying to look for shops in town for the smoothest experience.

North America

Frequencies in the Americas (ITU region 2, in blue) differ from the other continents

GSM (from the handful of major North American carriers that offer it) operates most often on 850 MHz/1900 MHz. AT&T and all three Canadian majors (Bell/Telus, Rogers) use 850 MHz/1900 MHz for their 3G (UMTS/WCDMA) networks. These are not the standard frequencies on other continents. Additional frequencies are used by new entrants, regional carriers or high-speed mobile data services.

AT&T and T-Mobile (USA) are GSM. European handsets might roam onto these carriers (for a price, usually fairly steep) if they support local frequencies and the home carrier permits it. 3G (UMTS/WCDMA) is supported by more carriers than GSM, but frequency assignments vary widely. An unlocked quad-band GSM or UMTS handset should be able to take a local SIM at destination. AT&T shut down its 2G network in 2017 and will shut down 3G in February 2022. T-Mobile, which purchased Sprint in 2020 and has now folded the Sprint brand into its own (though the two networks will not be fully integrated until mid-2022), plans to shut down Sprint's 2G CDMA network in January 2022 and its own 2G GSM network by the end of 2022. Rogers in Canada has shut down its 1900 MHz 2G network as of June 7, 2021, and its 850MHz 2G network will follow at the end of 2021.

Mobile subscribers in the US and Canada must pay airtime for all calls, in or out. (This is not true in Caribbean nations.) Handsets are assigned local, geographic numbers; one may switch from wireline to wireless service and keep the same number. Calling to a mobile telephone therefore costs the same as calling to a landline. A prepaid SIM will not work until "activated" by phone or (with some providers) on-line, as the subscriber must choose a city (which need not be their place of residence) from which to obtain their local inbound number.

AT&T, Verizon, T-Mobile (in the US) and Bell/Telus (in Canada) operate national networks, so roaming is usually not an issue within the country. Taking a Canadian handset into the US can be an expensive ($1.50/minute) misadventure as, unlike the European Union, there is no legal limit to what providers can charge for roaming. Downloading large amounts of data abroad has cost some users hundreds of dollars or worse. In addition, Rogers does not have its own network in the northern province/territories of Canada, and relies on "extended" coverage provided by Bell/Telus or Ice Wireless, which is not available to users with prepaid Rogers SIMs (visitors), so plan ahead and get a Bell/Telus SIM or you'll have to buy a separate prepaid SIM from Ice Wireless while in northern Canada. Meanwhile, competition within the US market has led providers there to significantly reduce what they charge for roaming to Canada; for example, Verizon prepaid costs $2 extra per day of use in Canada, T-Mobile prepaid plans can roam in Canada for only $5 extra a month, and AT&T doesn't charge any additional fees on plans that cost $40 or more to use them in Canada, making them the better choice for visitors planning on going to both countries.

There are a few small regional carriers; due to increased competition they generally don't charge extra for domestic roaming outside their home region anymore, but prepaid top-up cards are likely not in stores outside their home coverage area.

North American providers are notorious for flooding the market with branded handsets which are SIM-locked to one carrier on both pre-paid and post-paid services. A common tactic is to advertise an inexpensive (or even "free") handset in large print, while the fine print obligates the subscriber to a credit application for an expensive post-paid mobile subscription which takes years to pay off. Prepaid handsets are widely available at a reasonable initial price, but in Canada will carry a higher per-minute rate and inflated prices for mobile data (a dime a megabyte on low-end Canadian prepaid handsets, or a monthly bundle with 1GB for $30, is not unusual). In the US, prepaid plans are generally cheaper than postpaid at the expense of lower network priority, resulting in slower data at peak times.

For travellers and infrequent users, prepaid is likely the only viable option. There is a confusing array of brand names; some are major carriers, some are "mobile virtual network operators" (which resell bandwidth on the network of a major carrier, at a lower price), some are merely one of the majors rebranded under another name to give the illusion of competition. Prepaid minutes from one brand won't work with the others, even if they're using the same underlying carrier.

Refills (in the US) or top-ups (in Canada) for prepaid cards are generally available at convenience stores, filling stations, big-box retailers, pharmacies and Canadian post offices. It is often possible to refill using a credit card online. Some store-brand virtual operators (such as Loblaws or Petro-Canada in Canada or Walmart Family Mobile in the US) sell through their own stores (selected locations) or online only. Long distance on basic low-end prepaid plans is expensive ($0.25/minute airtime + $0.25/minute for a domestic long-distance call is the norm on the low-end "local" or "provincial" prepaid plans in Canada, while Internet telephony would cost a penny or two for the same call); it may be cheaper to use data-only service in conjunction with a VoIP provider like TextNow (US/Canada) or Google Voice (US only). There are also extra-cost plans to extend the meagre data allotment on prepaid mobiles. Direct-dial overseas calls (or calls to former +1 809 points in the Caribbean) are expensive on prepaid plans and best avoided.

Billing for calls usually begins when the call is dialled, not when it's actually answered; providers also round call lengths up to the next full minute.

Directory assistance is available at 4-1-1 or +1-area code-555-1212 but is expensive; advertising-supported competitor 1-800-Free411 or websites like 411.ca, 411.info or canada411.com are cheaper alternatives. Automobile association members may obtain mobile roadside assistance by dialling *222 (*CAA or *AAA); some specific services like #TAXI (#8294) will hail the next available cab in much of Canada or the US for a cost of $1.25-$2.

In the US, few retailers sell used phones; independent phone shops which can unlock a phone are rare outside large-city immigrant communities. Factory-unlocked handsets, used handsets and codes to unlock existing handsets may be purchased online, or if one feels comfortable, on marketplace sites like Craigslist or Facebook Marketplace.

Prepaid GSM SIM cards can be found at not just the stores of US mobile phone providers, but also many major retailers like Target, WalMart, and Best Buy. T-mobile offers one ($10) at their own shops or online, AT&T offers a SIM-only prepaid package on their website and stores. Another option is buying the least expensive prepaid phone; if you intend to move the SIM card to your own unlocked handset, do not insert the SIM into the phone supplied as (on AT&T "GoPhone") that will lock the SIM into that phone.

Some online services will ship prepaid SIMs overseas or ship specialised "travel SIMs" to North American addresses, but typically overcharge badly (for example Telestial or Cellular Abroad).

Asia

Some providers in China use TD-SCDMA (an incompatible alternative to W-CDMA on 3G UMTS handsets) or TD-LTE (as an alternative to LTE on 4G devices). TD-SCDMA is quite rare, but most devices will support TD-LTE as it has also been adopted in many countries outside China.
For visitors in India, getting a SIM card requires copies of passport and a few photographs. The procedure itself is easy, but the wait time from completion to activation may not be the same day. A 6 GB 4G data with 3 month calling can be availed for INR 350 (~US$ 5)
Japan and South Korea had no 2G GSM coverage, but adopted the UMTS standard for 3G, and most modern phones with 3G capability on the local frequencies should be able to roam there (South Korea has both 3G CDMA2000 and UMTS coverage).
Japan will generally not allow sale of SIM cards to foreigners on visa waiver or short term visas unless it is data-only; in general, your options are roaming (with a compatible LTE or 3G phone), renting a phone, or using a data-only SIM. This can be done at the major airports (Narita, Kansai, probably others) or via delivery to your hotel or business. Expect to pay $1–2 (¥100–200) a day, plus fairly high per-call/per-minute rates. For data-only SIMs, prices vary wildly as some providers charge anywhere from less than ¥5,000 (ca US$50) for unlimited data for 7-days to a total of more than ¥10,000 (ca US$100) for a SIM and a mere 5 GB of data good for one month, so do some research on this before leaving for your trip. There are a couple of providers that can sell voice-capable SIMs to short-term visitors, but they charge dearly for the privilege, with Mobal charging ¥4,500 (ca US$45) for just 7 GB data with an additional per-minute charge for outgoing calls and SMS.
South Korea now sells prepaid SIMs to short-term visitors also, with voice as well as data. However, not all SIMs can be activated after business hours, so check the details of the product you're buying if you're arriving at night or on a weekend.
Visitors to Singapore can buy a SIM card from currency exchange stalls, service centres of the TelCo providers or 7-11 convenience stores. However, they are required to give their passport at the point-of-sale for the service to be activated. A user is allowed to have a maximum 3 Singaporean SIM cards registered to his name at a time.
In Thailand, all three of the major providers have stalls at the big gateway airports (Bangkok, Phuket) selling tourist plans, and these can be a good deal depending on your data usage. However, if you're the bargain-hunting type or planning on continuing to another country afterward, consider looking for a convenience store that sells non-tourist SIMs in the airport instead; non-tourist SIMs from the three big providers can roam in neighboring countries for as little as 99 baht (~US$3) for 2 GB, and 399 baht (~US$13) for 7 GB in much of the rest of Asia, and have access to a rotating selection of promotions separate from the tourist SIM lineup.
Major UAE carrier Etisalat has stores in both Dubai Airport (Terminal 1) and Abu Dhabi Airport. Purchase requires a passport.
Tourist SIMs are available at Bahrain International Airport - SIMs otherwise require a valid residence ID that must be renewed annually for prepaid.
Makeshift SIM card stalls are available after exiting customs in most Philippine airports. Globe and Smart SIM cards are the ones most commonly available there. The Philippines has required registration of all SIM cards since 27th December 2022. Travellers can do this online through the official websites of the telecom provider that their SIM is connected to. This is a requirement to activate their SIM card. They will need a copy of their passport, entry passport stamps, and details of their Philippine address. SIM cards of travellers on short-term visits will expire after 30 days but those who are allowed to stay beyond that may apply to extend the life of their SIM card upon upload of pertinent documents.

Australia/Oceania

3G usually on 900/2100 MHz (Telstra is 850/2100) and 4G on 1800 MHz and 700MHz.
Note that Australia has some "external territories" served by separate providers than Australia proper, where you'll need to buy a separate prepaid SIM, if the option is even available (some don't sell service to visitors).

Europe

See also: European Union#Connect

In the European Union calls, messages and data should initially come out of your plan's domestic allowances if you have an EU-based SIM card, but there are still a lot of important exceptions and caveats. Most importantly, roaming may not be enabled at all with some cards, and in some cases operators are allowed to charge a (moderate) roaming surcharge. Surcharges are also allowed if you use the card extensively in countries other than the one the SIM pertains to – more use abroad than domestic use during a 4-months period. See ec.europa.eu for some details on EU roaming.

The EU rules on roaming do not cover calling a foreign number from the SIM's home country. If you are visiting several countries or use the SIM to call home, or European friends, make sure those calls are covered or check the separate price list.

Registration of SIM cards in Germany is now compulsory before they can be used. If you want to register your SIM at the same time as you purchase it, you need to purchase the SIM directly at a store operated by a telco (click on these for T-mobile, O2, and Vodafone shops) or its appointed partners (click on these links for a list of Lebara's and Lycamobile's partners) and bring your passport with you as registration involves verification of your identity. Although the process may sound daunting, the user does not have to be a German resident to purchase a German SIM card. T-Mobile can be quite picky though about requiring proof of address, so it's recommended to go with O2 or Vodafone, or if one needs the coverage, a reseller like Lebara.

When purchasing a prepaid French SIM card, activation is required. The user will have to follow instructions that came with the French SIM card, which either instructs the user to log-on to the provider's website or contact a hotline. Certain SIMs for short-term visitors may be activated without identification, but will automatically de-activate after 30 days if no identification is provided.

Visitors to Italy are required to produce a passport when purchasing a SIM card in order to have the service activated. In some cases, a photocopy of the passport may be all that is sufficient - this is at the merchant/retailer's discretion. You can purchase prepaid SIM cards at foreign currency stalls and at stores of mobile phone providers. You may also be asked to provide an Italian tax ID, but an unofficial version, sufficient for purchasing a prepaid SIM, can be generated online.

You can purchase UK prepaid (known here as "pay as you go") SIM cards at vending machines right before baggage claim in Heathrow Airport. Supermarkets and off-licence stores also sell SIM cards and top-up vouchers. Specialist mobile phone providers such as Lebara, Vectone and Lycamobile offer good rates for frequent overseas calls. At special events and public festivals, representatives of mobile phone providers give SIM cards out for free but you need to top up the required credit. Providers such as GiffGaff only operate online but their SIM cards can occasionally be found at certain events. Note that with Brexit taking the UK out of the EU-wide "roam like home" arrangement, UK providers are no longer obligated to include EU roaming in their service plans and most indeed have re-imposed EU romaing fees.

Given the dispute over whether the Crimean Peninsula belongs to Russia or Ukraine, and given Russia's de facto control over the peninsula, most mobile phones that do not have a Russian SIM card will not work on the peninsula.

Stay safe

See Phone service#Stay safe for emergency numbers and Rip-off networks above.

If you depend on your smart phone for maps, tickets and money, make sure your batteries don't go flat. Have some backup in case it gets broken or stolen.

A mobile phone may be expensive in itself, but the information in it and the contracts associated with it can be even more valuable. Even if you buy a throw-away phone, you should consider the risk of it being lost, stolen or cracked.

Modern phones usually have at least three authorization codes: for the phone, for using the SIM and for privileged configuration (of the SIM). These are set independently of each other. The SIM works by a PIN, the phone may provide fingerprint authorization or face authentication to access its features. The SIM PIN may be blank or trivial (0000, 1234) unless set to something else. These may also be preset by the provider with several random digits and given to you in a sealed envelope or packet. If you use a memory card without encryption, the card can be read and used once it is put in another device.

If your phone is locked, but your SIM isn't, a thief can simply take out your SIM, put it in their phone and make calls on your plan. Some phones use the SIM for locking the phone: replace the SIM and the phone is unlocked.

On the other hand, if you lock phone and SIM and forget your PIN (or get your finger bandaged or whatever), getting them unlocked can be more trouble than you'd like. Knowing the phone's PIN but forgetting the SIM's PIN, you may still access your phone but you may not be able to make calls or access mobile data. The phone can usually be reset to factory defaults, losing any information or photos you stored on it. The SIM card has a PUK code, which can be used to reset the PIN. Usually you either get it with the SIM or the provider keeps it and tells it when needed. Good backups help recover from some of this.

If you have banking apps, passwords, or similar sensitive content on your phone, the phone being stolen or cracked can involve much more than the phone, your telephony plan and your photos.

In the United States of America and Canada, 4G LTE telephones compatible with wireless public alerting (WPA) can receive emergency alerts from various levels of government to warn of inclement weather, fires, natural disasters, terrorist threats and civil emergencies. Alerts are sent as (seemingly) regular SMS messages in some other countries. These alerts are geo-targeted and cannot be opted-out (assuming the phone is turned on) but there is no charge to receive them. If you get an "EMERGENCY ALERT/ALERTE D’URGENCE" message, follow its instructions.

Selfies

Selfies have become a ubiquitous part of society. What's the point of doing anything if you can't post a picture of it on social media? It's as if it didn't happen. Because of this, people have an insatiable desire to take selfies and often will dispense with all common sense in the pursuit of doing so. This can mean putting oneself in harm's way due to standing in a dangerous place or near a dangerous animal. Think about it for a second before making a mistake you will regret.

Also, if you use a selfie stick, check if your destination allows them; theme parks, concerts, museums, and sports stadia have all banned them due to safety issues or disruptions to other attendees.

Respect

When taking pictures, everything on taking pictures in general applies. In addition to privacy issues, taking photos can cause disruption, especially on serene occasions.

There are many situations where the phone should be kept silent, including often at museums and the like, as unexpected noise can change the ambience. Often also handling the phone should be kept to a minimum. Talking on the phone may be felt more disruptive than talking to your company; e.g. on some trains those who want to talk on the phone are referred to a "phone booth" or away from a "silent" compartment.