04-06-2021 05:49 AM
Can someone tell me exactly what SIP message or header inside a SIP message triggers the use of the Rerouting CSS on a SIP trunk for an incoming call that was transferred? We have a SIP trunk from an AudioCodes SBC to ME Teams and for various reasons we'd like to have transferred calls from MS Teams to the CUCM use the Rerouting CSS for that SIP trunk the calls comes in on to CUCM.
Also, can you point me to any documentation that provides detail on this? I found very general info about it on Cisco's web site but not any fine detail so we can know for sure what CUCM uses in a SIP message or what TYPE of SIP message it needs to see to trigger the Rerouting CSS. As I understand it, I 'think' it uses a REFER message to trigger the use of the Rerouting CSS and NOT for example, a referred-by header inside an Invite message, is that right?
This is an example of a REFER message sent by MS Teams to the AudioCodes SBC. I haven't yet gotten to the point where we can get the REFER message all the way to CUCM from Teams, via the AudioCodes SBC because of the config already in use, which we might change depending on what I learn here about what triggers CUCM to use the Rerouting CSS, but once I know for sure what CUCM needs to use the Rerouting CSS, I'd like to make changes and test it. So anyway, here's the REFER from Teams to the SBC. Is THIS what CUCM needs or is it something else? Any detail/examples of a SIP message you can give would be great.
REFER sip:+15132223333@us-voice-sbc..domain.com:5061;transport=tls SIP/2.0
FROM: <sip:+15132223333@us-voice-sbc..domain.com>;tag=b128ac22817b453c83c1af09484e7cd9
TO: <sip:+15132223333@company.domain>;tag=1c1309202146
CSEQ: 6 REFER
CALL-ID: 129036129964202161311@us-voice-sbc..domain.com
MAX-FORWARDS: 70
VIA: SIP/2.0/TLS 52.114.1.0:5061;branch=z9hG4bK7adc02e
CONTACT: <sip:api-du-a-uswe2.pstnhub.microsoft.com:443
CONTENT-LENGTH: 0
REFER-TO: <sip:+15137211700@sip.pstnhub.microsoft.com:5061;user=phone;transport=tls>
REFERRED-BY: <sip:sip.pstnhub.microsoft.com:5061
USER-AGENT: Microsoft.PSTNHub.SIPProxy v.2021.3.29.2 i.USWE2.5
ALLOW: INVITE,ACK,OPTIONS,CANCEL,BYE,NOTIFY
04-06-2021 12:00 PM
Looks like no one has replied this one. Personally, I think you need to upload the full trace so we can answer the question for ourselves by following the call. However, that refer message is enough to trigger a transfer. I have seen such refer messages trigger transfers with expressway/vcs. And if cucm is trying to use the re-routing css, you will also know if you have cucm detailed logs on because you will see cucm list the partitions in the css before throwing up an error when it does not see a partition that would permit the call.
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04-06-2021 12:32 PM
04-08-2021 02:43 AM
In case anyone is watching this of finds it later, Cisco TAC did confirm that CUCM must get a REFER message similar to the one below to trigger the use of the Rerouting CSS.
The number in the FROM header is the number that transferred the call and the REFER-TO is the number that the call was transferred to.
REFER sip:+15132223333@us-voice-sbc..domain.com:5061;transport=tls SIP/2.0
FROM: <sip:+15132223333@us-voice-sbc..domain.com>;tag=b128ac22817b453c83c1af09484e7cd9
TO: <sip:+15132223333@company.domain>;tag=1c1309202146
CSEQ: 6 REFER
CALL-ID: 129036129964202161311@us-voice-sbc..domain.com
MAX-FORWARDS: 70
VIA: SIP/2.0/TLS 52.114.1.0:5061;branch=z9hG4bK7adc02e
CONTACT: <sip:api-du-a-uswe2.pstnhub.microsoft.com:443
CONTENT-LENGTH: 0
REFER-TO: <sip:+15137211700@sip.pstnhub.microsoft.com:5061;user=phone;transport=tls>
REFERRED-BY: <sip:sip.pstnhub.microsoft.com:5061
USER-AGENT: Microsoft.PSTNHub.SIPProxy v.2021.3.29.2 i.USWE2.5
ALLOW: INVITE,ACK,OPTIONS,CANCEL,BYE,NOTIFY
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