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Sims_Krastev's avatar
Sims_Krastev
Copper Contributor
Jul 15, 2019

MS Teams Direct Routing - Internal call transfer failure

Hi all,   My organisation is planning a move to direct routing. We have an AudioCodes VE SBC. I've been working on this for awhile and got everything to a pretty decent state.   I've come across ...
microsoft teams
Lt_Flash's avatar
Lt_Flash
Brass Contributor
Aug 01, 2019

Matej_Maric 

 

It shows where to send INVITE to, but it doesn't have a DID or username in SIP R-URI so SBC can't figure out where to dial to. SBC uses PSTN-type dialing, so it needs some LineURI or DID to send INVITE to, like +44XXXXXXXX@sip.pstnhub.microsoft.com. Otherwise it can't decide what to put in SIP INVITE method as 'To' field. I've tried to update SIP INVITE to whatever is in REFER-TO header and send it back to Microsoft, but I was getting a 400 Bad Request back.

 

REFER-TO: <sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689><sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689>sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689</sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689></sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689><sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689></sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689>

 

There's no user part in this SIP RURI, only host. What should be put in To header? Contact header is obvious, it's our SBC Contact.

Matej_Maric's avatar
Matej_Maric
Copper Contributor
Aug 01, 2019

Lt_Flash 

 

the thing is that SBC should only respect Refer-to header by means of SIP. REFER comes without user part but it's still fair enough and legal. So what my SBC does as last resort to send INVITE out is DNS query for hostname in Refer-To and fills RURI and To in same fashion:

 

INVITE sip:sip.pstnhub.microsoft.com:5061;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689;transport=tls SIP/2.0
Via: SIP/2.0/TLS 192.168.65.100:5061;branch=z9hG4bKvahihb0040adpr8tb320.1
CSeq: 1 INVITE
Contact: <sip:sbc.customers.matejandfriends.com:5061;transport=tls>;sip.ice
From: <sip:+18572996345@sip.pstnhub.microsoft.com:5060;user=phone>;tag=11241SIPpTag011
To: <sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689>
Content-Type: application/sdp
Content-Length: 425
Referred-By: <sip:sip.pstnhub.microsoft.com:5061;x-m=8:orgid:bdc0511a-4a8d-48aa-bf1d-5ea6ef316e2a;x-t=2d88cb42-f810-417a-a0fc-80244a7fdd61;x-ti=9cfa2ad6-c73e-402d-b621-90d9af6ffea2;x-tt=ahr0chm6ly9hcgktzhutys1ldxdllnbzdg5odwiubwljcm9zb2z0lmnvbs92ms9uz2mvy2fsbg5vdglmawnhdglvbj9ky2k9yje2odmxntuwyjuwndg3mzk4nja4ndhlmgflyznimwq%3d>
Call-ID: 8f09e11d9183f754c525a0d4ce2aea46
Supported: replaces
Max-Forwards: 70</sip:sip.pstnhub.microsoft.com:5061;x-m=8:orgid:bdc0511a-4a8d-48aa-bf1d-5ea6ef316e2a;x-t=2d88cb42-f810-417a-a0fc-80244a7fdd61;x-ti=9cfa2ad6-c73e-402d-b621-90d9af6ffea2;x-tt=ahr0chm6ly9hcgktzhutys1ldxdllnbzdg5odwiubwljcm9zb2z0lmnvbs92ms9uz2mvy2fsbg5vdglmawnhdglvbj9ky2k9yje2odmxntuwyjuwndg3mzk4nja4ndhlmgflyznimwq%3d></sip:sip.pstnhub.microsoft.com:5061;transport=tls;x-m=8:orgid:fce2158f-0e99-4ff7-a0b3-5b6b87d16689></sip:+18572996345@sip.pstnhub.microsoft.com:5060;user=phone></sip:sbc.customers.matejandfriends.com:5061;transport=tls> 

 

and that's just enough...

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