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DaveChomi's avatar
DaveChomi
Iron Contributor
Nov 12, 2019

Teams Direct Routing - DTMF tones on Inbound Calls not working

The other day of Microsoft Direct Routing life in our enterprise environment and another nice issue appeared as reported from users. Might be it will help somebody.   Long story short: Microsoft ac...
Direct Routing
DTMF
Inbound Calls
teams
Matej_Maric's avatar
Matej_Maric
Copper Contributor
Nov 30, 2019

DaveChomi 

 

Tested this quickly and you are absolutely right! end to end negotiation for tel-event was 96 and MS still sends PT 101

 

while the very last SDP from MS was:

 

SIP/2.0 200 OK
FROM: sipp<sip:sipp@xxxxxx:5060>;tag=14806SIPpTag091
TO: sut<sip:+18579901522@sip.pstnhub.microsoft.com:5060>;tag=aea750caffffffff783ba42de1144988
CSEQ: 1 INVITE
CALL-ID: 1-14806@192.168.2.50
VIA: SIP/2.0/TLS 192.168.65.100:5061;branch=z9hG4bKjsrauu0050fbcetu5op0.1
RECORD-ROUTE: <sip:sip-du-a-us.pstnhub.microsoft.com:5061;transport=tls;lr>
CONTACT: <sip:api-du-b-usea.pstnhub.microsoft.com:443;transport=tls;x-i=ae3a478a-7b34-41e7-89a9-76d4539810ad;x-c=/v1/ngc/call/1f2c4d2429a35cd782ce74fac9e08a30/s/1/640ba63046144b878e093a46d3954236>
CONTENT-LENGTH: 1295
CONTENT-TYPE: application/sdp
ALLOW: INVITE,ACK,OPTIONS,CANCEL,BYE,NOTIFY
SERVER: Microsoft.PSTNHub.SIPProxy v.2019.11.28.2 i.USEA.0

v=0
o=- 0 1 IN IP4 52.114.73.200
s=session
c=IN IP4 52.114.73.200
b=CT:50000
t=0 0
m=audio 52284 RTP/SAVP 0 13 96
a=ice-ufrag:nTGe
a=ice-pwd:4T8BipohUSo0fd1z+Z/SOOfd
a=rtcp-mux
a=candidate:10 1 UDP 184544254 52.114.73.200 52284 typ relay raddr xxxxxx rport 50010
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:6WFePvmprtmBvE9ftmV9BhgDnF8JiOd7o/XNAxZ4|2^31
a=rtpmap:0 PCMU/8000
a=rtpmap:13 CN/8000
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-16
a=ptime:20

 

hope they pick it up soon
a=maxptime:200

  • DaveChomi's avatar
    DaveChomi
    Iron Contributor
    Dec 05, 2019

    You are also right Matej_Maric, I didn't provide OK message with final SDP assuming as not necessary as MS already offered my payload type, right...

     

    At the end I just forced on my SBC to use all the time 101 for Teams side. It was also confirmed to me as behind scenes conversations that they do not expect anyway nothing else than PT 101 from customers. 

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