Teams call transfer failed - Audiocodes VE

Dear Colleagues,

I have setup an Audiocodes VE Direct Routing SBC, but during the tests I noted that I was not able to forward calls. As I can see, during the REFER process there is a 488 Not Acceptable answer, because of media mismatch between the Mediant and the O365. The p2p calls are working properly in every direction.

Have you experienced this kind of problem?

I have attached the SIP log (in .xlsx format, since .txt is not allowed), and the participants are:

10055 – Teams (Transferor)

20055 – CUCM registered phone (Transferee)

80000 – Mediant registered phone (Transfer target)

Thanks,

Laszlo