Four-Wire Operation, Type
Two-Wire Operation, Type
Description
Signal
Pin
4
3
2
1
4
3
2
1
T1
T1
T1
T1
T
T
T
T
Tip,
audio
input/output
or
output
T or
T1
8
T
T
T
T
—
—
—
—
Tip,
audio
input
T
6
E
E
E
E
E
E
E
E
Signaling
output
E-lead
7
—
SG
SG
—
—
SG
SG
—
Signaling
ground
return
SG
8
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 Conductor
Ring Conductor
Pair
26
1
1
27
2
2
28
3
3
Cisco VG310 and Cisco VG320 Voice Gateways Hardware Installation Guide
OL-31292-01
77
Cable Specifications and Information
Analog Voice RJ-21 Pinouts