I have done all the changes to get teams working according to 

https://skalatan.de/en/blog/kamailio-sbc-teams#:~:text=Extend%20the%20MS%20Teams%20systems,Kamailio%20SBCs%20to%20MS%20Teams.

but i find when i send a call to teams they send a response back with service unavailable.

Can anyone guide me what I am doing wrong?

I have added the record route and confirm it is being sent

My setup is freeswitch -- kamailio --- teams