KR100279158B1 - Call Connection Method of Digital Private Switching System with Network Interfaces Supporting Different Phonetic Coding Methods - Google Patents

Abstract

The present invention relates to a call connection method of a digital private switching system, and to solve the problem that voice is distorted even when a call connection between a network interface and a terminal using a different voice coding scheme is not normally performed. In the call access method according to the present invention, there is a call origination request through a digital network interface (E1 PRI) from a terminal supporting a first voice coding scheme (μ-law) or the first through the digital network interface (E1 PRI). A user of a bearer capability information element included in a message according to the call origination request and a message according to the call origination request when a call reception request is made to a terminal supporting a voice coding scheme (μ-law). The value of the user information layer 1 protocol field is converted to transmit and receive the converted bearer performance information element as a call origination message (setup message) and a call receipt message (Hof message).

Description

Call connection method of digital private exchange system

The present invention relates to a call connection method of a private exchange system, and more particularly, to a call connection method of a digital private exchange system.

Private Automatic Branch eXchange (PABX) typically has a T1 trunk that is connected to the Public Switched Telephone Network (PSTN) via the T1 trunk, and can also accommodate multiple subscribers. A circuit (SLI: Subscriber Line Interface) is provided.

Meanwhile, with the development of digital communication technology, digital communication networks such as Integrated Services Digital Network (ISDN) have already been proposed, and private switching systems are developing in such a way that they can be connected to such ISDN. At present, most private switching systems are not only used with T1 trunks, but also with E1 PRI (Primary Rate Interface), which is a component that enables connection between a private switching system and a digital communication network such as ISDN. Here, the T1 trunk and the E1 PRI may be distinguished by various criteria, but may be distinguished depending on which voice coding scheme is typically used. That is, the T1 trunk is a digital communication network interface supporting μ-law speech coding scheme, and the E1 PRI is a digital communication network interface supporting A-law speech coding scheme.

In a private switching system including a T1 trunk and an E1 PRI (hereinafter referred to as a "digital switching system"), a call of a μ-law terminal is connected through a T1 trunk, or a call of an A-law terminal is connected through an E1 PRI. There is no problem because the call processing and the call are normally performed. However, when the call is connected to the μ-law terminal through the E1 PRI, the call is rejected or severe noise occurs because the voice coding schemes of the E1 PRI and the terminal are different. More specifically, when a μ-law terminal sends an E1 PRI and transmits a setup message according to the voice coding scheme of the terminal, the μ-law terminal calls the bearer capability information element (Bearer Capability IE) in the message. As the information is loaded. In this case, since the country is not an A-law call, the incoming call is rejected or the voice is severely distorted even if the actual call is made. This phenomenon occurs in the same way when a call is made to a μ-law terminal by E1 PRI in a large country.

Accordingly, an object of the present invention is to provide a method for enabling a call connection between a network interface and a terminal using different voice coding schemes.

Another object of the present invention is to provide a method for removing voice noise generated during a call between a network interface and a terminal using different voice coding schemes.

The present invention for achieving the above object is a call origination request through the digital network interface (E1 PRI) from the terminal supporting the first audio coding scheme (μ-law) or the first through the digital network interface (E1 PRI) 1) When there is a call reception request to a terminal supporting a voice coding scheme (μ-law), a message according to the call origination request and a bearer capability information element included in the message according to the call reception request are included. We propose a call connection method that converts the value of the user information layer 1 protocol field and transmits and receives the converted bearer performance information element as a call origination message (setup message) and a call receipt message (Hof message). do.

1 is a view showing the configuration of a digital private exchange system to which the present invention is applied.

2 is a diagram illustrating a processing flow of a PRI initialization operation according to the present invention.

3 is a diagram illustrating a flow of an outgoing call processing operation according to the present invention.

4 is a view showing a flow of an incoming call processing operation according to the present invention.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user or chip designer, and the definitions should be made based on the contents throughout the present specification.

Referring to FIG. 1 showing a configuration of a digital private switching system to which the present invention is applied, the PABX 100, a digital private switching system, includes a T1 trunk 120 for network connection with a PSTN and a digital communication network such as an ISDN or a private network. PRI 110 for the connection is included. At this time, the T1 trunk 120 and PRI 110 are network interfaces supporting the μ-law speech coding scheme and the A-law speech coding scheme as described above. The T1 trunk 120 forms a T1 link with a PSTN, and the PRI 110 forms an E1 link with an ISDN or private network. The PABX 100 also includes a subscriber circuit (SLI) 140 for accommodating subscribers, such as μ-law terminal 20, between T1 trunk 120 and SLI 140, PRI 110 and SLI 140, and extension calls forming a trunk line. And a switching circuit (TSW) 130 for controlling the formation of a call path between subscribers of the SLI 140 forming the path. The central processing unit (CPU) 150, which is not described above, controls the overall operation of the PABX 100. The CPU 150 reads only the ROM (Read Only Memory) for storing the system program of the PABX 100 and temporarily processes data processed when performing various operations. RAM (Random Access Memory) is stored.

Meanwhile, in FIG. 1, it should be noted that components such as a ring detector, a tone generator, a dual tone multi frequency (DTMF) transmitter, and a DTMF receiver, which constitute a general exchange system, are not shown.

2 is a diagram illustrating a processing flow of a PRI initialization operation according to the present invention. That is, the CPU 150 shown in FIG. 1 performs an operation of initializing the PRI 110 according to the processing flow as shown in FIG. 2 when the PRI card is mounted on the PABX 100. This process is implemented as firmware of ISDN PRI.

First, the PRI 110 turns off the A-law / μ-law conversion flag mounted in the form of a card in the PABX 100 (step S201), and then determines whether to convert the voice coding scheme. This decision is made by requesting the configuration data of the PRI 110 to the CPU 150 (step S202), and searching whether there is an A-law / μ-law conversion request in the configuration data of the PRI 110 transmitted from the CPU 150 ( Step S203, step S204). The A-law / μ-law conversion requirements are set in the PACX 100's MMC (Man Machine Communication) mode. If it is determined that there is an A-law / μ-law conversion request in the PRI 110 configuration data transmitted from the CPU 150, turn on the A-law / μ-law conversion flag (step S205), and then A-law / μ- In step S206, the switching circuit 130, which is a TSW (Time Switch Block), is initialized to perform law conversion. On the other hand, if it is determined that there is no A-law / μ-law conversion request in the configuration data of the PRI 110 transferred from the CPU 150, the switching circuit 130 is initialized normally (step S207).

3 and 4 are diagrams illustrating flows of an outgoing call processing operation and an incoming call processing operation according to the present invention. These processing operations are operations performed in the application layer of the PRI firmware after the initialization procedure according to the processing flow as shown in FIG. 2 is preceded. That is, only when it is determined whether to convert the voice coding scheme is performed, the outgoing call processing operation and the incoming call processing operation according to the present invention are performed.

First, an outgoing call processing operation according to the present invention will be described with reference to FIG.

If there is a call origination request from the μ-law terminal, which is a terminal supporting the μ-law speech coding scheme, the CPU 150 receives the call and requests the call setup from the PRI 110 (step S301). When there is such a call setup request, the PRI 110 first determines whether the A-law / μ-law conversion flag is turned on (step S302). If it is determined that the A-law / μ-law conversion flag is turned on, the bearer capability information element (Bearer Capability I.E.) in the call setup request message is searched (step S303), and the user information layer in this information element is checked. The value of the user information layer 1 protocol fiele is converted (S304). In this case, A-law converts the field value to μ-law, and μ-law converts the field value to A-law. After performing the conversion operation, the converted information element is loaded on the NS_SETUP_REQ primitive and transmitted to the layer 3 as a setup message (step S305). The transmitted setup message is transmitted to the A-law terminal 10 having a different voice coding scheme from that of the μ-law terminal 20.

Next, an incoming call processing operation according to the present invention will be described with reference to FIG.

When NS_SETUP_IN, which is a setup message indicating call reception, is transmitted from the A-law terminal 10 supporting the A-law speech coding scheme (step S401), the PRI 110 detects whether the A-law / μ-law conversion flag is turned on. (Step S402). If the A-law / μ-law conversion flag is turned on, the bearer performance information element in the setup message is searched for (S403). After the bearer performance information element is found, an operation of converting the value of the user information layer 1 protocol field included in the information element is performed (step S404). At this time, if the value of the field is A-law, the field value is converted to μ-law. If the field is μ-law, the field value is converted to A-law. After converting the value of the field, the converted bearer performance information element is loaded on the Hof message, which is a call destination indication message, and transmitted to the CPU 150. The result is a call forwarding message to μ-law terminal 20 that supports μ-law speech coding.

As described above, according to the present invention, even when the ISDN PRI (E1) call is attached and received to the μ-law terminal, the A-law / μ-law conversion is appropriately performed even when the voice coding scheme of the PRI and the terminal is different. It can be made normally, and can also solve the problem that the sound distortion (noise) occurs.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (3)

A call connection method of a digital private switching system comprising at least an analog network interface supporting a first voice coding scheme and a digital network interface supporting a second voice coding scheme, The call origination request when there is a call origination request from the terminal supporting the first audio coding scheme through the digital network interface or a call request request from the terminal supporting the first audio coding scheme through the digital network interface. And the user information layer 1 protocol field of the bearer performance information element included in the message according to the call request and the call forwarding request, and transmitting and receiving the converted bearer performance information element as a call origination message and a call forwarding message. Call connection method. A call connection method of a digital private switching system comprising at least an analog network interface supporting a first voice coding scheme and a digital network interface supporting a second voice coding scheme, Detecting whether a voice coding scheme flag is turned on when a call origination request is received from a terminal supporting the first voice coding scheme; Searching for a bearer performance information element in a message according to the call origination request when the speech coding scheme flag is turned on; Converting a user information layer 1 protocol field in the searched bearer performance information element; And transmitting the converted bearer performance information element on a setup primitive to a terminal that supports the second speech coding scheme. A call connection method of a digital private switching system comprising at least an analog network interface supporting a first voice coding scheme and a digital network interface supporting a second voice coding scheme, Detecting whether a voice coding method flag is turned on when a setup message indicating a call reception is transmitted from a terminal supporting the second voice coding method; Searching for a bearer performance information element in the setup message when the speech coding scheme flag is turned on; Converting a user information layer 1 protocol field in the searched bearer performance information element; And transmitting the converted bearer performance information element to a terminal side supporting the first voice coding scheme by putting the converted bearer performance information element in a call destination indication message.

Images