Forum Discussion
Teams with SBC no DTMF tones
Hi Matej_Maric
this is a bit strange.
well first of all you are saying it is question to Microsoft but I would see this as question to SBC vendor because you mentioned it's in reply message from SBC to Teams. I would really focus more on the SBC setup in this case.
We are using Audiocodes SBC and DTMF tones are working bothway, also using transcoding for Teams clients to leverage SILK 16khz.
(also using Media Bypass)
This is example of OK SDP response on provider's OK with SDP that is sent to Teams:
- a=ice-lite
- m=audio 51200 RTP/SAVP 104 101
- a=rtpmap:101 telephone-event/8000
- a=ptime:20
- a=rtcp:51201
- a=maxptime:200
- a=ice-ufrag:YvsyU9OSVT3XpZet
- a=ice-pwd:aGS4+u+UBXO+UL6sMwPaUYxb
- a=candidate:123861241 1 udp 2130706431 ,,,,,, 51200 typ host
- a=candidate:123861241 2 udp 2130706430 ,,,,,, 51201 typ host
- a=rtpmap:104 SILK/16000
- a=fmtp:104 maxaveragebitrate=50000; useinbandfec=0; minptime=20
- a=crypto:1 AES_CM_128_HMAC_SHA1_32
DaveChomi Matej_Maric So after trying all the possible steps to fix this, I thought let me put on my glasses 😛 and go through each and every config on Direct Routing Doc from Audiocodes, so found that Ice lite was disabled. So I enabled it and boom it started working, to make double sure that this was the cause, I disabled it and tested DTMF fails and when enabled it works. I know it doesnt make sense, but I think this is something to do with AC SBC version 7.20A.254.202. The POC AC SBC where all DTMF works with IceLite being disabled as well and the SBC version is latest - 7.20A.254.475. To conclude it looks like AC would have fixed this in latest version.
glad this works for you and likely as you say something got improved in recent AC patches. what I'm trying to say is that ietf recommends different handling, something that may seem to work lovely from outside is actually error prone under surface.
https://mailarchive.ietf.org/arch/msg/avt/Hx8rEwIQr9FYrTjP8D-TK41XCag
you don't want to deal with above unless is your last resort option. for those willing to make a deeper dive will be clear what I'm trying to say.
