Nortel MICS dropping SIP calls that are converted to PRI

[Tideman]

thread799-1675333
I am referencing a thread that sounds like the same issue. We have a MICS that has worked fine on PRI for years. Customer's provider recently switched to SIP trunks converted to PRI by a Cisco 2911 router. Most calls work fine. In fact it seems like the only calls the system drops are calls to numbers that are forwarded to a voice mail. You can call a phone number with no voice mail and let it ring all you want with no problems. The call will connect if a person answers fine. The trouble happens when you call a number like a cell phone and it forwards to a voice mail. Per the carrier the Cisco router sends a 183 Session Progress to the MICS and it then drops the call. On calls with no voice mail or that a person answers the 183 Session Progress is not sent. Instead the router sends alerts and everything is fine. The carrier is saying they can not block the Cisco from sending the 183 Session Progress. Anyone have anything similar to this or know if I can tell the system to ignore the 183 Session Progress. If not anyone familiar with a Cisco 2911 and know about stoping the 183 from being sent. Thanks

 

[SupportDude]

The 183 Progress is part of the SIP protocol.
The Norstar is operating under ISDN PRI protocol.
The Cisco is responsible for the interworking between SIP and ISDN.
Somebody needs to go through the router to determine what it is sending to the Norstar when it receives a 183 Progress on the SIP leg of the call. I believe it should map to an ISDN "Progressing" message.
Google SIP and ISDN interworking and you should find some info and diagrams.


-SD-

http://www.mysupportguy.net