Calling Extension numbers registered in CUCM from MS Teams

[Aswin S]

We currently have MS Teams to PSTN calling feature (Direct Routing - SBC). Would like to know how to make enable for MS Teams applications or MS Teams Room to call extension numbers registered under CUCM (Numbers internal within company)?

[Roger Kallberg]

If you intend to have these calls not traverse the PSTN you would need to have a connection between the two disparate systems. This is done by using an SBC to interconnect the two SIP services and then create the required configuration for call routing to send calls between these.

[Aswin S]

So you are saying,  Call from MS Teams goes to SBC and check the dial peer configured, match the dial peer having pattern of extension number and its destination IP as CUCM and call reaches CUCM you are meaning right?

Sample dial peer you are meaning

dial-peer voice 300 voip
description ***MS Teams to CUCM Extensions**
destination pattern 87.....                                     //7 digit extension we are uing all numbers starting from 87
session protocol sipv2
session target ipv4: <CUCM IP address>

Are my above understanding correct?

[Roger Kallberg · Accepted solution]

Pretty much, you’ll need direct routing between Teams and CM for the SIP trunk connection between the systems. The SBC is in the mix of that connection.