CUCM SIP Trunk to GSM Gateway SIP 403 Forbidden Q.850 Cause Code = 21

[ccg-collab1]

Hi All,

We configured a GSM Gateway on the Call Manager via SIP Trunk. 

I believe the configuration on Call Manager side is fine SIP Profile/Security Profile and SIP Trunk that pointed to IP Address of the GSM Gateway. However every time we dial, busy tone was always the result. As per checking on the gathered CMTrace, the CUCM is responding SIP 403 Forbidden Q.850 Cause Code 21. Could you help to analyze the CM Trace.

Please see attached CM Trace File.

===========================

Calling: 4998

Called: 09175118768

Time Stamp:

6:22
6:23
6:25
6:26

Thank you in advance

[romahaja]

Cause code - 21

Indicates one of the following:

• The equipment sending this cause does not wish to accept the call, although it could have accepted the call because it is neither busy nor incompatible.

• May be generated by the network, indicating the call was cleared due to a supplementary service constraint

Have you checked the configuration at the Gateway side ?  Check the IP address of CUCM at the gateway.I will go through the traces.