Table 17-3: RJ-21 Connections for the High-Density Analog Voice Network Module
RJ-21 Connector
Pair Tip Conductor Ring Conductor NM-HDA Port Network Module Reference
1 26 1 0 FXS
2 27 2 1 FXS
3 28 3 2 FXS
4 29 4 3 FXS Base card
5 30 5 4 FXS FXO
6 31 6 5 FXS FXO
7 32 7 6 FXS FXO
8 33 8 7 FXS FXO
9 34 9 8 FXS Unused
10 35 10 9 FXS Unused
11 36 11 10 FXS Unused
12 37 12 11 FXS Unused
13 38 13 12 Unused Unused
14 39 14 13 Unused FXO failover Expansion board in slot 0
15 40 15 14 FXS FXO
16 41 16 15 FXS FXO
17 42 17 16 FXS FXO
18 43 18 17 FXS FXO
19 44 19 18 FXS Unused
20 45 20 19 FXS Unused
21 46 21 20 FXS Unused
22 47 22 21 FXS Unused
23 48 23 22 Unused Unused
24 49 24 23 Unused FXO failover Expansion board in slot 1
25 50 25 -- Unused