US 4,907,258 AGranted

Key telephone apparatus

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorFukashi Kamitomo

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Abstract

A key telephone apparatus includes a main device which is connected to a telephone network line and a plurality of extension telephones connected to the main device. When the line dialed from the extension telephone is busy, the busy tone signal transmitted to the extension telephone is detected by a tone detection circuit provided in the extension telephone. In response to the detection of the busy tone signal, a controller provided in the extension telephone produces a redial command which is applied to a controller provided in the main device. Thus, a controller redials for the same line after a predetermined time interval. If the line is still busy as detected by the tone detection circuit in the extension telephone, the controller provided in the extension telephone sends the redial command to the controller provided in the main device which repeats the redialing after the predetermined interval.

Claims3

Dependent claims

A key telephone apparatus having a main device which is connected to a telephone network line and a plurality of extension telephones connected to said main device through a voice transmission line for sending voice signal and a data transmission line for sending control data, said key telephone apparatus comprising:

said main device comprising:
switching means for connecting at least one of said extension telephone with said telephone network line;
means for sending dial signal to said telephone network line in accordance with a dial command signal obtained from said extension telephone through said data transmission line;
means for connecting said telephone network line with said extension telephone through said voice transmission line in accordance with said dial command signal;
and
means for generating and sending a sound detection start command through said data transmission line to said extension telephone after the completion of sending said dial signal to said telephone network line by said dial signal sending means;
and
said extension telephone comprising;
inputting means for inputting a redial command;
tone detection circuit for detecting a tone signal transmitted through said voice transmission line from said main device;
means for generating and sending said dial command signal through said data transmission line to said main device in accordance with said redial command;
means, activated by said sound detection start command, for detecting a busy tone signal in an output signal from said tone detecting circuit;
and
means for regenerating said dial command signal when said detecting means detects said busy tone signal.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/336,906Filed 12 Apr 1989
Granted: 6 Mar 1990
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04M 9/002
Arrangements for interconnection not involving centralised switching: with subscriber controlled access to a line, i.e. key telephone systems
H04M 1/2749
Using static electronic memories, e.g. chips: automatic dialling or redialling systems, e.g. on off-hook or redial on busy
H04M 1/715
Substation extension arrangements: using two or more extensions per line
H04M 3/424
Systems providing special services or facilities to subscribers: arrangements for automatic redialling