The savings.
Annual cost of the Teams Phone Standard + UK Calling Plan stack vs. 3CX with Teams Direct Routing (which still sits on top of your existing M365 licence). Three SME sizes.
| User count | Teams Phone + Calling Plan / yr | 3CX Direct Routing / yr | Annual saving |
|---|
| 25 users | Microsoft~£4,950 | 3CX~£2,400 | ~£2,55052% reduction in telephony layer. M365 cost unchanged on both sides. |
| 50 users | Microsoft~£9,900 | 3CX~£4,800 | ~£5,10051% reduction. |
| 100 users | Microsoft~£19,800 | 3CX~£9,000 | ~£10,80055% reduction. |
Microsoft pricing snapshot May 2026 from microsoft.com/en-gb. Teams Phone Standard £6.30/user + UK Domestic Calling Plan £10.20/user = £16.50/user/mo for the telephony stack. 3CX numbers include licence + UK hosting + Gamma SIP + support — see honest pricing for the decomposition. Ex-VAT.
What stays the same after the switch.
The whole point of Direct Routing is that the Teams experience is identical:
- Users still dial from the Teams client. Same call button, same dial pad, same call history. No new app to install or train people on.
- Contacts and presence from Teams still drive call routing. "Is Sarah free?" still works. Voicemail still drops into Teams.
- Inbound calls land in Teams. Notifications work the same way. Call answer/decline buttons in the same place.
- Mobile Teams app keeps making and receiving calls. No separate softphone needed.
- M365 licence and Azure AD identity untouched. Same logins, same SSO, same audit trail.
What changes: the underlying call routing. Microsoft Calling Plan goes away; 3CX with UK Gamma SIP takes its place. Configuration is on the 3CX admin side, not visible to users.
What gets better after the switch.
Features Teams Phone doesn't include at the standard tier, which 3CX gives you for the same money:
- Advanced call queues. Reception queue with announced wait position, callback option, music-on-hold, overflow rules. Teams Phone has basic queues; 3CX has the full set.
- Call recording with retention policy. On-demand or always-on, per-extension, with configurable retention by call type. Cleaner than Teams Phone's recording (which sits on Microsoft Stream / OneDrive with less flexible controls).
- IVR designer with multi-level branching. "Press 1 for sales, then 1 for new business or 2 for existing customers, then route to the right team queue." Teams Phone's auto-attendant is single-level only.
- Hot desking. Real hot desking — sign into any handset and have your extension follow. Teams Phone has app-level identity but not handset-level hot desking.
- Switchboard / reception console. A dedicated reception UI showing all extension states, drag-to-transfer, queue depth at a glance. Teams Phone has nothing equivalent.
When to stay on Teams Phone.
Three honest cases:
- You're under 15 users and the calling needs are basic. Setup overhead for the switch isn't justified by £30–60/month of savings.
- You're in a single-vendor procurement culture. Some firms can't accept a new supplier on the principle of consolidation. Worth the cost premium if the procurement value is real.
- Your firm uses Operator Connect with a specific provider integration we wouldn't replicate cleanly. Operator Connect is Microsoft's alternative to Calling Plan; if your existing Operator Connect setup is working well and the cost is similar to 3CX Direct Routing, it's a fair tie.
Switching mechanics.
A Teams Phone → 3CX Direct Routing migration is the cleanest cut-over of any UK SME PBX switch, because the user-facing UX doesn't change. Typical 4–6 week timeline:
- Week 1 — audit and quote. We look at your Teams Phone usage (call volumes, user count, current call plan tier). Quote on the honest-pricing template.
- Week 2 — 3CX deployment. 3CX system provisioned on UK hosting. Direct Routing trunks configured to your Microsoft 365 tenant. SIP trunks ordered (Gamma).
- Week 3 — porting paperwork. If you have Microsoft Calling Plan numbers, those port to Gamma. If your numbers are already on a third-party SIP provider behind Operator Connect, they re-route to 3CX.
- Week 4 — cut-over. User assignments switch from Calling Plan to 3CX Direct Routing in the M365 tenant. End-users notice nothing — calls flow through 3CX from this point. Microsoft licences (Teams Phone Standard + Calling Plan) cancelled at next renewal.
- Week 4–6 — feature roll-out. Once basic calling is stable, enable the 3CX features (advanced queues, recording, IVR, hot desking) progressively. User training optional but typically half a day.
Common questions from Teams Phone leavers.
Do users have to install anything new?
No. Direct Routing is transparent to users. The Teams desktop, web, and mobile apps work exactly as before.
What about voicemail?
Configurable. Voicemail can stay in Teams (default) or move to 3CX's voicemail with email notifications. Most firms keep it in Teams for continuity.
What if my IT person doesn't know 3CX?
That's why we provide the managed-service layer. You don't need internal 3CX expertise. Day-to-day admin changes (add a user, modify a queue, change an IVR menu) we handle. Strategic changes we work through with you.
What's the contract risk?
Standard 3CX managed-service contracts run 24 months. You can keep your existing M365 contract running — nothing about it changes. If you want to come back to Teams Phone later, you can — the Teams client never went anywhere.
