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afouad5's avatar
afouad5
Copper Contributor
Nov 10, 2020
Solved

Teams Direct routing media bypass mode ICE controlled

I've a strange scenario when I enabled media bypass on my SBC and thought to check with everyone here first before contacting MS.   Outbound calls from Teams to PSTN works with ICE being CONTROLLIN...
CONTROLLED
CONTROLLING
ICE
media bypass
  • afouad5's avatar
    afouad5
    Dec 10, 2020

    AlainCPlease check https://tools.ietf.org/html/rfc5245#page-75

     

    "ice-lite" is a session-level attribute only, and indicates that an
   agent is a lite implementation.

    In your trace you have it within the media part , once you have it in the right position before m=audio

    you will get the correct controlled state and nomination.

AlainC's avatar
AlainC
Copper Contributor
Dec 10, 2020

afouad5 We are doing a POC with our own SBC to check interoperability. 

As you had the same issue and as it seems to be fixed now, what would be nice is to have a sip trace / debug logs  of an outbound successfull call. Bellow the configuration of our sbc in O365, maybe is there something wrong (we tried to enable BypassMode "Always", but no effect) ? :

 

 

 

 

 

 

 

 

 

Thanks

afouad5's avatar
afouad5
Copper Contributor
Dec 10, 2020

AlainCPlease check https://tools.ietf.org/html/rfc5245#page-75

 

"ice-lite" is a session-level attribute only, and indicates that an
   agent is a lite implementation.

In your trace you have it within the media part , once you have it in the right position before m=audio

you will get the correct controlled state and nomination.

  • AlainC's avatar
    AlainC
    Copper Contributor
    Dec 11, 2020

    afouad5 , many thanks, it works now 🙂

    • afouad5's avatar
      afouad5
      Copper Contributor
      Dec 11, 2020
      Perfect 🙂
      • AlainC's avatar
        AlainC
        Copper Contributor
        Jan 23, 2021

        Hello afouad5 

         

        With our SBC, everything works fine in media bypass mode except when the SBC sends a hold and retrieve (REINVITE with a=inactive for HOLD, REINVITE with a=sendrcv for RETRIEVE). Then we have a similar issue (one-way voice path)

        Description :

        - before the HOLD, the ice is completed and RTP flows are properly exchanged between the SBC and the Teams agent.

        - To the REINVITE offer with a=inactive, MS Proxy replies an answer with new candidates and c=media relay IP@. No REINVITE from MS Proxy to conclude the ice handshake. I guess it is normal, as the voice traffic is on hold. Voice traffic is stopped on both ways (OK)

        - To the REINVITE offer with a=sendrcv, MS Proxy replies an answer with the same candidates as the previous anwer

        - But no RE-INVITE from MS Proxy to conclude the ice handshake. The SBC receives RTP flow from teh MS client and sends flow to the Media Relay. The Teams client hears nothing but the voice path Teams client -> SBC is fine.

        - During all the session (before the HOLD, between the HOLD and RETRIEVE an after the RETRIEVE, the SBC receives STUN binding requests from the Teams client every seconds with ICE-CONTROLLING and the SBC properly answers to all these STUN requests

        - After around 20 seconds, MS Proxy sends a BYE with reason "CallEndReasonMediaError"

         

        Attached the sip trace (@IP replaced by XXXX for SBC and YYYY for the teams client)

         

        Thanks for your feeback

         

         

         

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