PSTN connectivity: Calling Plan vs Operator Connect vs Teams Phone Mobile vs Direct Routing
Verdict: Four PSTN models. Calling Plan makes Microsoft the operator with no infrastructure. Operator Connect and Teams Phone Mobile use certified carriers. Direct Routing keeps your own carrier and SBC, and is the only model supporting PBX interop and location-based routing.
| Criterion | Calling Plan | Operator Connect | Teams Phone Mobile | Direct Routing |
|---|---|---|---|---|
| PSTN operator | Microsoft, 99.999% SLA, US emergency screening | Certified third-party landline operator | Certified mobile operator, SIM number is the Teams number | Your own carrier via a customer-managed certified SBC |
| Infrastructure to manage | None | None | None | Customer procures and manages an SBC |
| Best fit | Small orgs wanting Microsoft to run everything | Keep an existing certified carrier, no SBC | Field workers on a mobile SIM | Keep current carrier, interop with third-party PBX and analog equipment |
| Location-Based Routing (toll bypass) | N/A | N/A | N/A | Supported (only here) |
| SMS on the number | US and Canada only | No | No | No |
Rules
- A Teams Phone licence enables calling features; a separate PSTN solution supplies the number and PSTN access.
- Calling Plan is the only model where Microsoft is the operator, with a 99.999% SLA and US emergency screening.
- Choose Direct Routing to keep the current carrier and interoperate with a third-party PBX and analog paging.
- Location-Based Routing to restrict toll bypass is supported only under Direct Routing.
- A tenant can combine all four models by persona; a single connectivity type is not required.
- SMS in Teams works only on Calling Plan numbers in the US and Canada.
Traps
- There are exactly four PSTN models; Shared Routing Connect is not one of them.
- On-premises PSTN connectivity needs only Teams Phone Standard; do not add a Calling Plan licence.
- Cloud Voicemail auto-provisions without a Teams Phone licence, into the user's Exchange mailbox.