Solved Teams Direct Routing internal transfer issue

[Vincent van der Meer]

Hi,
We recently started our Teams Direct Routing with 3cx as SBC. Everybody is very happy to use Teams for handling their calls. Only there is one issue .

If we transfer a call (in Teams) to another Teams user. The transfer fails...
Apparently Teams Telephony System refers the call to the SBC rather than handling the call internally.

So the call flow is as follows:
Incoming call from SBC to MS Teams -> MS Teams user transfers the call to internal user -> Call fails as MS Teams generates a REFER back to the SBC rather than route the call internally to MS Teams user target. (I have attached the log files from 3cx, while attempting a transfer)
(see also: https://techcommunity.microsoft.com...ing-internal-call-transfer-failure/m-p/754902, from here I copied the line above and below )

A workaround would be to disable REFER as an allowed method within the SBC's signaling messages, then MS Teams does not use REFER for transfers and just re-INVITEs to the SBC. That way the internal transfers work perfectly fine.

However in 3cx this is not an option (without some code hacking), since the Direct Routing Trunk is not visible in the admin console.

Does anybody have some idea how to approach this (or apply the workaround) within 3cx?

Vincent

 

[Vincent van der Meer]

O, by the way: The workaround seems to work with other SBCs

 

[Evolute IT]

This is a known issue that will be fixed in a later update, probably U1 or a hotfix after that.

The integration is still Alpha so give them some time

 

[NickD_3CX]

Hi!

As Frederick said, there are still some transfer scenarios that between Teams clients that don't work, but will try to get them fixed for V18 U1 final.

for the time being ,we have released V18 U1 Beta that does have certain improvements in this area, if you want, you could give it a shot!
https://www.3cx.com/community/threads/v18-update-1-beta-fine-tuning-teams-integration.84237/

 

[Vincent van der Meer]

Thanks, will discuss the implementing of the beta in our 3cx installation.

Still very happy with the integration though