This configuration is a bit old, and I am unclear on the Nortel configuration (SBC did it for us at the time), but the following worked for us on a VG200 and CMM in a 6500 chasis.
interface Serial1/1:23
no ip address
no logging event link-status
isdn switch-type primary-dms100
isdn incoming-voice voice
isdn bind-l3 ccm-manager
isdn channel-id invert extend-bit
no cdp enable
Also, make sure you are using a crossover cable for T1's (1&2,4&5) if your not already.
-Matt
