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New Member

SIP call Routing Issue

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?

VIP Super Bronze

Re: SIP call Routing Issue

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.

Please remember to rate helpful responses and identify helpful or
New Member

Re: SIP call Routing Issue

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: <885558>;tag=3492934351-718907
To: <0967401>;tag=F136BCEC-1C90
Date: Wed, 08 Sep 2010 11:32:34 GMT
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.

New Member

Re: SIP call Routing Issue

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.


New Member

Re: SIP call Routing Issue

Just to add something more..

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

Cisco Employee

Re: SIP call Routing Issue

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

New Member

Re: SIP call Routing Issue

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.