To connect Teams Phone to the PSTN, you can choose from the following options:

 To connect Teams Phone to the PSTN, you can choose from the following options:

Calling Plan. An all-in-the-cloud solution with Microsoft as your PSTN carrier.

Operator Connect. With Operator Connect, if your existing carrier participates in the Microsoft Operator Connect program, they can manage PSTN calling and Session Border Controllers (SBCs).

Teams Phone Mobile. With Microsoft Teams Phone Mobile, a user’s SIM-enabled phone number is also their Teams phone number. If your existing carrier participates in the Microsoft Teams Phone Mobile program, they can manage the service for bringing PSTN calling to Teams.

Direct Routing. Enables you to use your own PSTN carrier by connecting your Session Border Controller(s) (SBCs) to Teams Phone.