The staged path that works
Every safe Teams migration follows the same shape. Audit: your 365 licensing (much is often already paid for), current numbers and call flows, and who actually needs what. Choose the route: Operator Connect for most, Direct Routing for scale and complexity. Build alongside: Teams calling is configured and tested while your existing system keeps working — pilot users prove it in real traffic. Port on an agreed day: numbers move in minutes, the old system stays as a safety net briefly, then retires. The whole arc typically runs two to four weeks, of which your team notices roughly one morning of 'phones feel different'.
What catches people out
The honest trap list: assuming the Teams licence you have includes Phone (it usually needs adding); forgetting the analogue stragglers — door entry, alarms, lift lines — that need their own plan before the old lines cease; under-planning call queues and reception, where Teams' native tools are decent but different; and cancelling the old provider before porting completes (never — a cancelled number can be lost). We've run this migration enough times that the checklist runs itself; your job is choosing the go-live date.
Related: Teams Phone (pillar) · Operator Connect · Direct Routing · Teams Phone cost
Frequently asked questions
How long does a Teams Phone migration take?
Typically 2–4 weeks end to end, mostly parallel-running and testing. The user-visible switch is a morning.
Can we keep desk phones with Teams?
Yes — Teams-certified handsets exist and work well for reception and desk-heavy roles. Most staff end up preferring the app; the choice is per person.
What about our door entry and alarm lines?
They need identifying and re-homing (usually onto dedicated services) before old lines cease — it's on our audit checklist precisely because everyone forgets them.