Strange Problem: Fixed line calls ok, mobile calls keep ringing

[koksiong]

CCM 3.3(3):

I have 2 CCM connected to 2x Cisco3745 gateways with 6 x ISDN lines for voice.

When I dial into call manager using a fixed line phone, everything works ok.

But when I use a mobile line to call into call manager, I can hear a secondary dial tone on my mobile, but the call is already put thru on the IP Phone (IP Phone user can hear the mobile user talking, but mobile user hears a secondary dial tone). Also to note is that this problem does not occur all the time, Sometimes, mobile calls work ok, but other times, they dont function properly.

I need help to know where to start troubleshooting, and is there a difference in how CCM handle fixed line call and mobile calls?

[pacameron]

It could be the mobile network is passing or processing ISDN progress messages differently to the fixed network. Can you post the output for debug isdn q931 for a fixed call and a a mobile call so we can see the difference.

[koksiong]

Attached are the debug on my 2 gateways.

One thing I cannot understand is that sometimes mobile calls work, and sometimes they don't. I suspect it could be some timing issues, but I need some pointers to what timers are these.

[pacameron]

One of the calls has a progress indicator in it, the other does not. Try adding the following command under the VOIP dial peer/s that point to the call manager -

progress_ind setup enable 3

This command forces the gateway/router to treat the inbound ISDN Setup message as if it came in with a PI = 3 and to generate an in-band ringback tone towards the calling party if the H225 Alert message does not contain a PI of 1, 2 or 8.

Also add the global config command -

voice rtp send-recv

this cuts through the audio path in both direction before a connect message has been received.