Resolution
To connect a Cisco 2801 router with PBX using a T1 connection, use a T1 cross-over cable.
There are T1 cross-over cable pinouts:
- pin 1 to 4
- pin 2 to 5
- pin 4 to 1
- pin 5 to 2
For more information, refer to the Digital Voice Port Pinout (RJ-48C) section of Cisco Digital 1-port and 2-port T1 Multi-Flex Voice WICs.
