We have had some severe teething problems deploying direct routing with our SBC. we now have a successful connection when calling into teams... but not when calling out. When calling out the call is disconnected after 3 seconds with a response code 488. looking at the report in teams the only difference is:
Where as a failed call shows FAILED in these fields... Is this a media bypass issue?
I think it is some configuration error, not Media Bypass. Media Bypass is not used or supported for Direct Routing yet.
488 could be that the phone numbers you send in the SIP INVITE is not formated the way that Teams want it, you should check the fields for to, from, contact and p-asserted-identity. It could also be codec problem, so that your SBC and Teams don't use the same codecs.
You should check the SIP logs at your SBC to start with, there you will be able to see more about the 488 error and what caused it.
Thanks for the input.. Just to update..Proxy Relay was added in the supported media section on the SBC. Turned this off and all was fine.... Its a little frustrating given the length of time we have been playing with it... But this seems to work for us now... Calls flowing like a champ! Now the fun REALLY begins!
@WelshViking Could you tell me where is the SBC section. I haven´t found the field "proxy relay" on the output of cmdlet "get-csonlinepstngateway". Actually we are facing a similar problem, but in our case is about outgoing call, when the call is put on hold, the call is dropped. We have seen a 488 message with text message "back to back bypass offer was declined by peer".