BT One Phone replacement: your options now it's switched off

What replaces BT One Phone?

For most small and mid-sized BT customers, the closest replacement is BT Cloud Voice, already built to handle many of One Phone's capabilities such as supporting desk users, hunt groups, inbound calls and Auto Attendant. However the absence of One Phone's mobile work capabilities (for field staff and area managers) is better replicated by BT Cloud Voice plus BT Business Mobile. Further to this, where businesses are already heavily using Microsoft 365 products, switching to Teams Phone via BT becomes a more ideal route to hosting all workflows in one place.

Netify groups those choices into our Three-Path Replacement Matrix:

• Path A is BT Cloud Voice as the main replacement.
• Path B is BT Cloud Voice plus BT Business Mobile.
• Path C is Microsoft Teams Phone via BT.

We'd suggest that the best option for your business is likely far less dependent on pricing and more on how staff actually used One Phone every day.

Stay with BT, or leave? Start here

Whilst Netify has been a BT Authorised Partner since 2012, most guides on this topic assume a business will stay with BT. We would rather give the wider view of every available route.

For businesses staying with BT, this is typically the lowest-friction option: existing numbers, the existing BT commercial relationship and account management are all preserved, and the choice narrows to the three Cloud Voice paths below.

For businesses open to leaving BT, this can be a reasonable route where teams are mobile-first, where pricing is a concern, or where the wind-down of One Phone has prompted a wider review of communications. The main UK alternatives are compared further down this page.

The BT Three-Path Replacement Matrix

Path A. BT Cloud Voice as a like-for-like replacement

BT Cloud Voice is BT's primary offering for replacing BT One Phone, designed to fit the needs of mostly desk-led businesses (with occasional mobile use). It's worth noting that features do vary based on BT Cloud Voice's feature packs (Basic, Connect and Collaborate), with an optional Webex Premium add-on on Collaborate. Across those feature packs, BT offers capabilities such as:

• Hunt groups,
• Call transfer,
• Auto Attendant,
• Call Centre ACD,
• CRM integration through CRM Integrator or CRM Lite,
• Cisco Webex meetings up to 1,000 participants on Premium.

Entry pricing for BT Cloud Voice starts at £10.52 per user per month (on a sixty-month contract), though the actual pricing will depend on the user mix, as feature pack set, handset choice and connectivity options.

Our recommendation is that, if most users answered calls from a fixed location (e.g. a desk) and require business features over mobile-first behaviour, BT Cloud Voice (Path A) is usually the best fit.

Path B. BT Cloud Voice plus BT Business Mobile

Alternatively, for those businesses who are more mobile-first and may not be suited to the fixed location basis of Path A, BT Cloud Voice plus BT Business Mobile is a better fit for the likes of field engineers, sales teams, mobile account managers and service staff (who are rarely at a desk). With this setup, BT Cloud Voice handles the desk and call-management layer, whilst BT Business Mobile handles mobile, making it capable of replicating much of the business outcome of One Phone (even if it does not recreate the architecture).

Although architecturally different to One Phone, BT Cloud Voice plus BT Business Mobile can keep one supplier relationship, preserve business numbers and core call-routing features, alongside also giving mobile users the freedom they need for continuing current operations.

Path C. Microsoft Teams Phone via BT

Finally, for organisations already leveraging Microsoft 365 for much of daily operations and are keen to reduce app sprawl, Microsoft Teams Phone via BT can be an ideal replacement for BT One Phone. With this, BT can deliver Teams Phone through a calling plan layered onto existing Teams licensing, or through Operator Connect, with BT supplying numbers and calling services inside the Teams environment, making voice part of the same application already used for chat and meetings.

Typically we'd suggest that this path is more aimed towards larger businesses as it also introduces a Microsoft licensing and administration conversation that smaller firms often do not want.

What customers keep, lose and gain

What stays

In our experience, customers will typically keep business numbers (through standard BT porting), with crossover within around 4 hours on the cutover day. On top of this, customers also get to keep their BT commercial relationship, which can be useful for businesses with multi-site billing, other BT services or a named account manager.

What goes

Whilst the business numbers stay, customers will lose the network-level SIM-and-extension architecture that was provided by One Phone, as well as losing having a single portal that combined both the mobile and PBX offerings into a single place. Furthermore, if businesses previously used MobileIron Cloud as part of their previous setup, device security will need to be additionally addressed.

What arrives

BT Cloud Voice enables a greater handset range than BT One Phone, with handset options including:

• Poly VVX 150,
• Poly VVX 250,
• Poly VVX 450,
• Poly CCX 500,
• Yealink T43U,
• Yealink T46U,
• Yealink T48U,
• Yealink T54W,
• Yealink CP920,
• Poly Trio 8300,
• Yealink W53 DECT solution.

On higher tiers of the BT Cloud feature sets, businesses can also gain access to Cisco Webex meetings for up to 1,000 participants, CRM integration and Call Centre ACD for distributed service teams.

What a realistic migration looks like

For many small and medium businesses, moving from BT One Phone to BT Cloud Voice often takes four to eight weeks from order to go-live, whilst larger multi-site deployments often run eight to twelve weeks. Within this period, the first stage consists predominantly of audit and design, followed by provisioning and number planning and then the final stage, cutover and porting, with numbers usually live within four hours.

In our experience, the most common delay is down to uncertainty over which feature-pack to choose. Whilst Netify can assist with this, the following simple rule helps in most cases:

• Runs meetings: Collaborate.
• Joins meetings: Connect.
• Answers inbound calls from a fixed spot: Basic.

The Netify BT One Phone Migration Assessment

Here at Netify we utilise a five-step process known as The Netify BT One Phone Migration Assessment to help assist in the process.

1. Usage Audit - Within this we review total users, SIMs, call flows, in-building coverage needs and which staff actually depend on each feature.
2. User Classification - Split users into desk-majority, mobile-majority and hybrid settings, allowing mappings to Path A, B or C (BT Cloud Voice, BT Cloud Voice plus BT Business Mobile or Microsoft Teams Phone via BT).
3. Number Portability - Within this, check every number, hunt group and shared ringing pattern before any replacement route is approved.
4. Hardware and Device Management - Confirm which desk phones, conference phones and cordless devices are needed, as well as whether any mobile device management layer needs replacing.
5. Commercial Review - Check contract end dates, any remaining commitment and whether BT withdrawal changes the commercial position.

At the end of the five steps of the migration assessment, you should find yourself with a recommended replacement path, an indicative quote and a realistic migration timeline.

Leaving BT? The main UK alternatives compared

For businesses open to moving away from BT, the credible UK options for a One Phone replacement are below. Netify works with a number of these providers through its marketplace, and we would suggest comparing them on the same basis as the BT paths above, starting with how staff actually worked on One Phone day to day.

• PiPcall is a mobile-first UCaaS provider. BT has worked with PiPcall on a replacement service for One Phone customers, and it is positioned as a like-for-like mobile successor with number porting and UK support. It is strongest where staff genuinely work on mobile for the majority of their time.
• Gamma is an established UK UCaaS and cloud telephony provider with a broad channel presence, generally well suited to desk-led and hybrid teams.
• 8x8 is a global UCaaS platform with significant contact-centre depth, worth considering for multi-site and service-heavy operations.
• Vonage is a flexible cloud communications platform with strong application and API options for businesses with more specific integration requirements.
• ONSIM is a mobile-first alternative positioned specifically against One Phone, with number porting and UK support included.

Why do people buy from an Authorised BT Business Partner?

An Authorised BT Business Partner sells the same BT services on the same BT paper: the contract, the billing, the support and the network all stay with BT. The difference is commercial and practical. Partners hold pre-approved BT discounts that BT direct sales typically cannot match without escalation, and a named specialist designs the deal, handles the BT paperwork and manages the order through to go-live.

• Pre-approved partner discounts, applied through BT's own internal pricing tools.
• The same BT contract, BT bill and BT support as buying direct.
• Specialist design, migration planning and order management included.
• Verifiable status: BT publishes its official Authorised Partners list so buyers can check exactly who they are dealing with.

About Netify, the BT Authorised Partner behind this page

Netify has worked in the BT channel as a BT Authorised Partner since 2012 and is BT Cloud Voice Partner of the Year for FY 2025/2026, awarded by BT Business. The team behind this page runs The Netify BT One Phone Migration Assessment described above: usage audit, user classification, number portability, hardware and device management, and commercial review.

BT's own Authorised Partners page features Robert Sturt, Netify's Managing Director, on the partnership, and links back to netify.co.uk. Read it at business.bt.com/bt-authorised-partners.

On price, Netify runs BT's internal Cloud Voice discount calculator, the route to pre-approved partner discounts, and confirms a best-and-final migration price in writing, typically within one working day. BT direct sales typically cannot apply these partner rates without escalation.

Your contract and billing remain with BT throughout. Netify designs the deal, secures the discount and manages the migration; BT provides the service, the bill and the support, exactly as it would if you bought direct. Same BT, better price, with a specialist doing the work.

Arrange your migration call

Final recommendation

For most former BT One Phone customers, whilst it can be obvious to move to BT Cloud Voice from BT One Phone, it can be less obvious which Cloud Voice product to move to. The first question is whether the business was desk-led, mobile-led or Microsoft 365-led and once that is clear, the path is usually clear as well.

Netify recommends BT Cloud Voice as the default replacement for most desk-led BT One Phone customers, BT Cloud Voice plus BT Business Mobile is stronger where mobile work sat at the centre of the old setup and Microsoft Teams Phone via BT is best for organisations already committed to Microsoft 365 and willing to accept more setup complexity.

For businesses open to leaving BT, a mobile-first operation will often find PiPcall or ONSIM the closest fit, whilst desk-led and hybrid teams, or those with multiple sites, should look at Gamma, 8x8 or Vonage.

We would recommend starting with the assistant above, then requesting pricing based on actual users, feature packs and handset requirements.