Technical Data
INSYS Modem 56k small INT 2.0/USB 1.0
92
June 06
14.6
Telephone Interface
Layout of the RJ12 Connector and the RJ45 Jack
Pin
Description
Pin
Description
1 NC
4
b1
2 a2
5
b2
3 a1
6
NC
Meaning of the Signals:
a1, b1: Incoming phone lines
(e.g. exchange connection or PBX)
a2, b2: They are used to connect a telephone in series. In idle state, a2 and b2
are connected with a1 and b1 via a loop current connector. a2 and b2 are
disconnected as soon as the modem occupies the line.
RJ 12 connector directed
backwards
RJ 12 connector front
b2 b1
a2 a1