[cisco-voip] Service Provider SIP Trunks

[Aaron Banks]

I have a strange problem with SIP trunks.  Let me preface this with the service provider moved the SIP trunks to a different device and that's what certain calls stopped working.  Before this move, everything was tested and working for 6 weeks.  Read on, someone might have had the same experience.

Post SIP trunk move, callers inside of the organization cannot call 911 or a mobile phone (ANY mobile phone).  When they dial the number, let's use 911 for example, the call rings once, the calling line ID is delivered to 911 and then the call goes to busy.  So 911 knows that organization called.  The same thing happens with mobile phones.  All other call types (local, LD, international) work.  If I call forward a phone from inside of the organization to a mobile phone and call that forwarded phone (from outside or inside), the call is redirected to the mobile, call is answered and then the call drops.  If I forward that same phone inside of the organization to an outside land line ((either local or LD), the call is successful.

For 911 or the mobile calls that fail, the SIP trace reveals a 500 (internal server error), a BYE message with reason Q.850; cause=16.  The SIP call messages show the state of the call is DEAD.

My question is why would the number make any difference at all?  Has anyone ever seen this type of issue before?  The provider says it is CUCM 10.5/Voice GW 2901 that is rejecting the call.  I disagree.

Many thanks

Aaron

 		 	   		  
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