Core Issue
There are two scenarios in which this problem is seen:
- When an Cisco IP phone calls out to a Nortel PBX, the caller ID is displayed on the Private Automatic Branch Exchange (PABX) phone, but the calling name of the Cisco IP phone is not displayed.
- When a PABX phone calls into a Cisco CallManager Express IP phone, the caller ID is displayed on the IP phone, but the calling name of the PABX phone is not displayed.
Resolution
To resolve this issue, perform these steps:
- Upgrade to Cisco IOS Software version 12.4(4)XC, in which the Q.SIG Supplementary Services were introduced in Cisco CallManager Express.To download 12.4(4)XC, visit : Cisco IOS Software Under voice service voip, configure the Q.SIG decode to enable Application Protocol Data Unit (APDU) encoding and decoding for the facility IE.
Note: After these two steps are completed, the Cisco IP phone can display the calling name from Nortel.
- If the caller ID is still not displayed, the cause could be that the PBX is using a different Q.SIG type that cannot decode the message.
Cisco CallManager Express sends/encodes the calling name in the ISO Q.SIG format, and is able to decode the other Q.SIG types (like ECMAv3 and ECMAv1). It appears that the far-end Nortel PABX is using ECMAv1 Q.SIG and cannot decode the ISO Q.SIG callng name.
