Re: Sip calls from CME sent to Provider with wrong header...

f.giordano · ‎09-10-2010

Hi All,

I have an issue with a CME 7.0 on a 2821 platform. This customer is currently using E1 PRI to dial outside but he would like to try Sip call from local provider. So I did the configuration of the SIP Trunk. My gateway is registered and incoming calls to ephone ( sccp ) are working.

However I noticed a strange behaviour with outgoing call.

Here is what happen:

Cisco 7941 SCCP phone with extension "91" (registered to CME) place a call over the SIP trunk.

If I make a debug ccsip message, I can see the first packet sent (which is INVITE) has a completely wrong header (I believe):

Here is the first Outgoing Packet:

INVITE sip:00352XXXXXXXX@register.XXXXXXXX.com:5060 SIP/2.0
Via: SIP/2.0/UDP 10.10.10.254:5060;branch=z9hG4bK8E2259
From: "CCC" <sip:91@register.XXXXXXX.com>;tag=5C29C8-24F4
To: <sip:00352XXXXXXXX@register.XXXXXXXX.com>
Date: Thu, 09 Sep 2010 12:08:42 GMT
Call-ID: D2DC5702-BB4111DF-8149FC31-1482ACE2@10.10.10.254
Supported: 100rel,timer,resource-priority,replaces,sdp-anat
Min-SE: 1800
Cisco-Guid: 3506494421-3141603807-2168781873-344108258
User-Agent: Cisco-SIPGateway/IOS-12.x
Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY, INFO, REGISTER
CSeq: 101 INVITE
Max-Forwards: 70
Timestamp: 1284034122
Contact: <sip:91@10.10.10.254:5060>
Expires: 180
Allow-Events: telephone-event
Content-Type: application/sdp
Content-Disposition: session;handling=required
Content-Length: 355

My CME Address: 10.10.10.254

Sip Provider Address: register.XXXXXXX.com

My ephone-dn used: 91

So my question is: Why do I see at the top of the packet From: "CCC" <sip:91@register.XXXXXXX.com>

I guess I'm supposed to see From: "CCC" <sip:91@10.10.10.254>

Fyi, all me DN on CME are configured with "non-reg both" command.

Any Idea ????

Thanks

Fabian

dksingh · ‎09-10-2010

Hi Fabian,

I think the From: header is that way as the GW is perhaps registered with the SIP provider's proxy?

You'd notice CME's IP in the Contact: and Via header.

no-reg option in ephone-dn works only for GK registration (H.323 scenario)

We'd need following to investigate failed outbound SIP further :

deb ccsip mess

deb voip ccapi inout

sh run

sh sip-ua reg stat

Thx.

DK

f.giordano · ‎09-13-2010

Hi Dilip,

I'll be on customer site tonight and will be able to take the debug you asked for.

I'll post them tonight.

Thanks

Fabian

f.giordano · ‎09-13-2010

Hi,

here is the output you asked for.

Thanks for your help

Fabian

dksingh · ‎09-13-2010

Hi Fabian,

I looked through IOS debugs and here's what I see...

GW sends Invite with....

Call-ID: 4CB2EB13-BE8411DF-8051C03B-9D8C8F95@10.10.10.254

But the responses (100/183/200 etc.) coming back shows:

Call-ID: 4CB2EB13-BE8411DF-8051C03B-9D8C8F95@0.0.0.0

So IOS will not be able to match the transaction and perhaps will
trash these (debug ccsip all wil confoirm.) It is as if no response
was received to our Invite and that's why we see so many Invite
(re)transmission.

Also note that the VIA header in 1xx responses are also invalid:

Via: SIP/2.0/UDP 0.0.0.0:5060;branch=z9hG4bK11B3A;received=10.10.10.254

You should check with the SIP provider on above but first check if ITSP can get to GW IP 10.10.10.254 or is it being NATed?
What other devices are there between the GW and ITSP ?
See if they can pull a trace on their end and compare with this to see how the headers look/what IP addrs. show up in there.

Hope this helps.

DK

f.giordano · ‎09-14-2010

Hi Dilip,

Thanks for your analysis.

We have a Cisco ASA between the 2821 and the SIP Provider. I'm not sure this device is responsible of the wrong Sip packet since incoming calls are working fine, but we'll have a look. We have a conf call tomorrow with the Provider in order to compare the packets on the two sides.

Thanks again

Fabian