JPH0444786U - - Google Patents

Description

[Brief explanation of drawings]

The drawing is a block diagram showing an embodiment of the present invention. Main symbols, 1...Telephone system, 2...Main phone, 3...Slave phone, 4...Doorphone slave, 10
1 to 105... Switch, 106... Extension current supply circuit, 107... Control device, 108... Door phone control circuit, 109... Loop detection circuit, 111
...Futsuku switch.

Claims (1)

[Scope of utility model registration request] It has its own telephone circuit and at least one telephone is connected thereto, or at least two telephones are connected thereto, thereby essentially accommodating a plurality of telephones and further accommodating a doorbell. A telephone system comprising: an extension communication path that connects the plurality of telephone systems in a branch connection format; an extension current supply circuit connected to the extension communication path and supplying communication current to the extension communication path; A hook detection means is provided corresponding to each of the plurality of telephones, and includes a hook detection means for detecting the hook state of each telephone, and a doorphone control circuit for controlling the connection of the doorphone to the extension communication path via the extension current supply circuit. The telephone system has a switch means inserted in each branch path of the extension communication path to each telephone, and an incoming doorphone call occurs when an extension call is being made between any two telephones. , when one of the telephones that is engaged in an extension call responds to an incoming door intercom call, the switch means is inserted into a branch route other than the branch route to the telephone that detects on-hook and then off-hook again after the hook state detection means detects on-hook; An interrupt prohibition circuit for intercom calls is configured to open the circuit to separate the branch path from the extension current supply circuit.