Forum Discussion
MS Teams Direct Routing - Internal call transfer failure
Also, maybe your SBC has a rule to remove Refer-To header and sometimes that rule is applied by incorrectly configured Match policy? Have you tried sniffing traffic and decoding TLS to see the actual SIP packet coming from MS before it's handled by SBC?
Lt_Flash I don't think that the SBC removes the refer, because when I do it via the Teams Client, everything works fine. If I disable Referred-By on the SBC transfers stop working, even internal Teams Transfers. I'm not sure who to do TLS sniffing and decoding. What do I need to do? Run wireshark while i transfer and filter for TLS/TCP packets?
It's not that easy, you will need your SSL certificate and private key in order to decrypt the traffic, you need to google about that. But maybe you just disable REFER support like we did? That's much simpler and works much better and requires less rules on SBC to make calls work. Just strip 'REFER' from any 'Allow:' header coming from SBC on requests and responses.
It turned out, that there was in fact something wrong with how Microsoft / 3PIP SfB Phones sent the refer to our SBC. (Our SBC did not receive a refer-to number) Microsoft has now fixed the issue and we can correctly transfer calls to external numbers via the Teams Desktop Client and 3PIP Modes with users in TeamsOnly mode.
Hi mate,
Good to know it's all fixed! Yes, the biggest problem when dealing with Microsoft is that you never know if that's an issue with your phone or software or with their end. I was speaking to their official support as we are an official partner and all I got in the end was 'Please post into our techcommunity'.