Sep 17

Cannot dial out to ISDN – Destination Incompatible

I recently came across a problem where I could dial mobile numbers via an ISDN 30, I could also use csim start command to dial out to local, national and mobile numbers. However I could not dial local, national or International numbers from an 8945 IP Phone.

Debuggin ISDN Q931 I received the following output:

Bearer Capability i = 0x8890A3
Standard = CCITT
Transfer Capability = Unrestricted Digital
Transfer Mode = Circuit
Transfer Rate = 64 kbit/s
Channel ID i = 0xA9839F
Exclusive, Channel 31

Error – Destination incompatible.

The solution was to configure the bearer capability on the voice-port for the E1. The 8945 was sending video capabilities to the carrier and the carrier was rejecting the call.

I entered the below command on the voice-port sub interface
Bearer-cap speech.