Telephone circuit
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Dec 30, 2003
Grant Date -
N/A
app pub date -
Jul 5, 2000
filing date -
Jul 5, 1999
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Disclosed is a telephone circuit in which two simultaneously available telephones are connected by use of a pair of twisted-paired cables. A PBX 1 and a digital multi-function telephone 2 are connected by a pair of twisted-paired cables, a digital signal channel of 2B+D is established bidirectionally between the PBX 1 and the digital multi-function telephone 2, and user information and a control signal are sent and received therebetween. The digital multi-function telephone 2 and an analog telephone 3 are connected by a pair of twisted-paired cables, and a signal is sent and received between the digital multi-function telephone 2 and an analog telephone 3 by an analog signal of a voice band and a DC/AC control signal. A B1-channel on a 2-wire digital line 4 is allocated for user information transmission of the digital multi-function telephone 2, and a B2-channel is allocated for user information transmission of the analog telephone 3. A D-channel signal is shared by control signals of both the telephones. A bidirectional 2B+D digital signal is sent and received by a proper transmission system such as a ping-pong transmission system.
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