SIP call Routing Issue

Unanswered Question
Sep 8th, 2010

Hi all,

I am having a weired issue and need help.

Call flow:

Dial 0967401 >>> Hit SIP Gateway ( >>> Number translates to 7401 >> Reach CUCM >> Route Pattern 7401 with Route List for another 2800 Gateway (

Call is coming in fine and hitting the Call manager but I cannot see any activity at the 2nd gateway. I turned on deb voip ccapi inout but the 2nd gateway showed no activity whatsoever. This number is a fax number and the fax machine is attached to a FXS port at 2nd gateway ( There is no way I can make fax work if the call does not hit the 2nd gateway.

I have verified that the call is definitely hitting the CUCM as I forwarded the number to my mobile and it rang when I dialled the main DDI.

Both gateways can ping Call manager and Call manager can ping both gateways.

I have reset the gateways and Route List as well.

Any clue why it is not working?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Jonathan Schulenberg Wed, 09/08/2010 - 04:23

Is the route pattern in the Calling Search Space of the incoming SIP trunk on UCM?

What error code is UCM returning to the originating router? You can see this using a 'debug ccsip messages' and will see a 400, 500, or 600 fatal response from UCM.

asharsidd Wed, 09/08/2010 - 04:38

Hi Jon,

The call ends with a dial tone...long one...and these are the messages.

1398425: Sep  8 11:32:36.802: //-1/xxxxxxxxxxxx/SIP/Msg/ccsipDisplayMsg:
SIP/2.0 503 Service Unavailable
Via: SIP/2.0/UDP 83.x.x.81:5060;branch=z9hG4bK3defb2f5743e8c15bc8edf36dd4bf603
From: ;tag=3492934351-718907
To: ;tag=F136BCEC-1C90
Date: Wed, 08 Sep 2010 11:32:34 GMT
Call-ID: [email protected]
Allow-Events: telephone-event
Server: Cisco-SIPGateway/IOS-12.x
Reason: Q.850;cause=41
Content-Length: 0

Attached you will find the complete ccsip trace.

asharsidd Wed, 09/08/2010 - 04:41

Sorry forgot to tell you.

RP is 7401 in Partition PT_FIX_Internal.

The SIP gateway has Inbound CSS as CSS_FIX_RSTD which contains partitions PT_FIX_Internal and PT_FIX_RSTD.


asharsidd Wed, 09/08/2010 - 05:21

Just to add something more..

I asked someone Internally to dial 7401 and first he got engaged tone and then complete silence...

Steven Holl Wed, 09/08/2010 - 07:46

We need to find out why the GW is throwing a 503.

What is the topology of this?  Is this a SIP-to-SIP CUBE?  Or is there an H323 leg?  Or is it CUCM-SIP-GW-FXS?  It's not clear.

Can you send:

sh run

sh ver

And then get:

debug ccsip all

debug voip ccapi inout

debug h225 asn1 (if you are running h323)

debug vpm sig (if there is an analog line)

debug isdn q931 (if there is a pri)

Collect debugs in the following manner:

Router(config)# service sequence
Router(config)# service timestamps debug datetime msec
Router(config)# logging buffered 10000000 7
Router(config)# no logging con
Router(config)# no logging mon
Router(config)# voice iec syslog

Router# term len 0

Router# sh logg

asharsidd Wed, 09/08/2010 - 15:53

Thanks Guys for all your help.

I have resolved the issue myself.

For some reason the Fax Gateway was not accessible from the SIP gateway. The Ping was successful but I was not able to telnet. Something in between was blocking the communication. I bypassed Call manager and created a VOIP dialpeer with session protocol sipv2 and pointed it to another IP address of that fax gateway which was accessible. As the other interface was binded to H323, I had to make this dialpeer as SIPv2 and the issue was resolved.


This Discussion