Digium G100 - Digium, Inc; Table A-2: RJ45 T1;E1 Port Connector

Digium, Inc. Page 60
Appendix A: Pin Assignments
All RJ45 (8P8C) ports labeled T1/E1 on the Gateway Series
appliance are 8-pin. RJ45 jacks are also commonly referred to as
RJ48 when used for telecommunication. The pin assignments are
identified in Table A-2.
Table A-2: RJ45 T1/E1 Port Connector
Pin Description
1Rx Ring
2Rx Tip
3 Unused
4 Tx Ring
5Tx Tip
6 Unused
7 Unused
8 Unused
Pin 1
Pin 8