Support SIP URI calling from other PBX's
Currently the only way to route calls from existing PBX's to TEAMS is via Direct ROuting SBC and e.164 dialling.
We need tgha ability for this connection to support SIP URI calling between the platforms.
This was supported in Skype for Business and was used when a customer had multiple platforms, such as CUCM.
This blog describes the desired operation : https://voipnorm.blogspot.com/2013/06/updated-cucm-sip-uri-dialing-to-lync.html