Cisco RJ-21
Cisco RJ-21

Cisco multi-port voice gateways have one or more ports for analog phones which is called RJ-21. Since the distance between the Cisco voice gateway and the phone distribution frame can be variable, you may need to make a special cable to connect these ports.

You can see the RJ-21 port and pin order used in Cisco multi-port analog voice gateways in the following image:

Cisco RJ-21 Connector Pinout

In the table below, you can find the pin sequence of RJ-21 ports used in Cisco multi-port analog voice gateways:

Port Number Connector Pin Signal
1 1
26
Ring
Tip
2 2
27
Ring
Tip
3 3
28
Ring
Tip
4 4
29
Ring
Tip
5 5
30
Ring
Tip
6 6
31
Ring
Tip
7 7
32
Ring
Tip
8 8
33
Ring
Tip
9 9
34
Ring
Tip
10 10
35
Ring
Tip
11 11
36
Ring
Tip
12 12
37
Ring
Tip
13 13
38
Ring
Tip
14 14
39
Ring
Tip
15 15
40
Ring
Tip
16 16
41
Ring
Tip
17 17
42
Ring
Tip
18 18
43
Ring
Tip
19 19
44
Ring
Tip
20 20
45
Ring
Tip
21 21
46
Ring
Tip
22 22
47
Ring
Tip
23 23
48
Ring
Tip
24 24
49
Ring
Tip
25,50,51,52 GND