Four-Wire Operation, TypeTwo-Wire Operation, TypeDescriptionSignalPin
43214321
T1T1T1T1TTTTTip,
audio
input/output
or
output
T or
T1
8
TTTT
————
Tip,
audio
input
T6
EEEEEEEESignaling
output
E-lead7
—
SGSG
——
SGSG
—
Signaling
ground
return
SG8
Analog Voice RJ-21 Pinouts
The following figure shows RJ-21 connector wiring for a 50-pin Amphenol cable.
Figure 23: RJ-21 Connector Wiring
The following table lists the pinouts for the RJ-21 connector.
Table 25: Pinouts for FXS and FXO Voice Ports
Tip ConductorRing ConductorPair
2611
2722
2833
Cisco VG310 and Cisco VG320 Voice Gateways Hardware Installation Guide
OL-31292-01 77
Cable Specifications and Information
Analog Voice RJ-21 Pinouts