3CX Gamma Horizon or RingCentral for a UK Small Business Before the 2027 Landline Switch-off

Openreach's analogue network switches off on 31 January 2027, with no extension, so any UK office still on copper lines needs a cloud phone system, not just a new handset. For an eight-person office, 3CX costs from about £3 to £16 a user a month depending on hosting, Gamma Horizon runs roughly £10 to £13 through an accredited partner with calls included, and RingCentral starts at £12.99, though most offices need its £19.99 tier. Choose on management, not price alone.

Key pointers

• The switch-off date of 31 January 2027 is fixed. Openreach says there is no extension and has already raised its wholesale line rental price twice in 2026 to push stragglers off copper.
• Business lines do not get the same fallback protection as some residential lines after the deadline, so an office cannot simply wait and see.
• 3CX licenses by simultaneous call, not by user, so a single licence can cover far more extensions than staff who are ever on the phone at once.
• Gamma Horizon is never sold direct. Get quotes from at least two accredited partners, because the same platform can carry a different price and service level depending on who sells it.
• RingCentral's cheapest Essentials plan drops video, call recording and Microsoft 365 or Google Workspace integration, so check what is missing before comparing headline prices.
• Ask each supplier for the full monthly cost once your calling minutes, handsets, SIP trunk and integrations are added, not just the entry-level figure.
• Start porting your existing number now. Number porting and testing typically take one to three weeks either way.

What a Cloud Phone System Means for a Small Office

A cloud phone system replaces the physical PBX box and copper lines in the comms cupboard with software that runs calls over your internet connection. Staff get a business number on a desk handset, a laptop app or a mobile app, and calls can be answered from any of them. For an office coming off analogue, this is the point of the switch, not video calling or AI notetaking, which vendors sell hard but a small office may never touch.

The three systems in this comparison solve the same core problem in different ways. 3CX is software you or an IT partner run, so you own the configuration and can move it between hosts. Gamma Horizon is a fully managed service delivered by a local partner, aimed at businesses that want one phone call to fix a problem. RingCentral is a global self-service platform with the deepest feature set and the most integrations, aimed at businesses that already use tools like Salesforce or Microsoft 365 and want the phone system to plug straight in.

Before comparing prices, decide what you actually need: enough inclusive UK calling minutes for your call volumes, a mobile app so staff can work away from the desk, call recording for compliance, CRM integration, and, in most small offices, very little else. Anything past that is a supplier's upsell, not a requirement.

The 2027 Deadline and Why Waiting Gets More Expensive

Openreach confirmed the PSTN switch-off date of 31 January 2027 after pushing the original end-of-2025 date back to give vulnerable customers more time to migrate. The company has been explicit that there will be no further delay. James Lilley, Openreach's Director of All-IP, said in July 2026 that "the PSTN switch-off is now just six months away and there is no extension to the deadline" and urged businesses to "speak to their service provider today, understand which services could be affected, and make sure they have a clear migration plan in place well before January 2027."

Around 1.5 million UK lines were still on the old network at the end of July 2026, of which roughly 350,000 were business premises. Unlike some residential lines, which get a temporary emergency-calling fallback if they miss the deadline, business lines have no equivalent protection and simply stop working once the switch flips.

Staying on copper is also getting more expensive in the meantime. Openreach's wholesale line rental rose 20% on 1 April 2026, then a further 40% on 1 July 2026, and is set to rise again on 1 October 2026, which Openreach says will double the original rental price it charged providers. Those increases feed through into what a business pays for an analogue line, on top of the fact that Openreach stopped selling new WLR lines in September 2023, so an existing line cannot simply be replaced or added to.

For a UK small business, the practical read is this: the deadline is real, the old service is already getting dearer, and a business that leaves it to the last few months risks losing dial tone with no fallback, not just paying more for a while.

Pricing and Cost Model

None of the three systems is priced the same way, which is exactly why the like-for-like comparison matters.

3CX charges per system, based on the maximum number of simultaneous calls (SC) it needs to handle, not per user, and a fair-use policy caps the number of extensions to that SC tier rather than allowing unlimited users. An 8 SC Professional licence, capped at 40 extensions, costs £330 a year from a reseller pricing the platform at 3CX's own UK rates. Professional already includes video conferencing for up to 100 participants, call recording and full Microsoft 365 integration; the Enterprise/AI edition, at £480 a year for the same capacity, adds Microsoft Teams direct routing, skill-based routing and AI features such as call transcription and an AI receptionist. There is also a genuinely free tier, 4SC Basic, for up to 10 extensions with core calling only. The licence fee does not include hosting or a SIP trunk for external calls, both bought separately from a hosting provider or IT partner. One VoIP consultancy's independent estimate puts a fully managed, hosted 3CX deployment at from £8 a user a month, plus a SIP carrier for calls typically adding £3 to £8 a user a month, which is roughly £11 to £16 a user a month all-in for a small managed setup.

Gamma Horizon is sold only through accredited partners, so the retail price varies by reseller even though the underlying platform is identical. One Gamma partner's indicative pricing runs from around £9.95 a user a month for the Standard package up to £17.95 for the fully-loaded Unified package, with the Pro tier (adding free VoIP handsets and mobile apps) at £12.95. Every tier includes a call bundle of 2,000 free UK landline and 2,000 free mobile minutes per user per month, a fully managed install, and UK-based hosting. That same independent cross-vendor review puts Gamma Horizon overall at £12 to £18 a user a month, which sits comfortably around the Pro tier and above once handsets and mobile apps are included.

RingCentral publishes UK list prices for its RingEX platform directly. On annual billing, Essentials starts at £12.99 a user a month but includes only 100 outbound minutes a user, with no video meetings, call recording or third-party integrations with Microsoft 365 or Google Workspace. Standard, at £19.99 a user a month, is the tier most small businesses actually need, adding 750 outbound minutes a user, video meetings for up to 100 participants, and on-demand call recording. Paying annually rather than monthly saves up to 38%; check RingCentral's current plan pages for the exact minutes and features included, since providers revise these allowances.

Assumptions for the worked example

For an eight-person office (all with an extension, but unlikely to be on eight simultaneous external calls at once), an 8 SC 3CX Professional licence is generously sized. £330 a year divided by 12 months gives £27.50 a month for the whole system; divided across 8 users, that is £3.44 a user a month for the licence alone, excluding hosting and call charges.

3CX Gamma Horizon and RingCentral Compared

Gamma's own Horizon product page states a 99.95% SLA for Horizon itself, alongside a 99.999% uptime claim for its wider network, but does not publish service credit terms, so get those confirmed in your partner contract rather than relying on the marketing page. RingCentral's own reviewer-verified figure puts its uptime SLA at 99.999%. Neither figure is independently audited in the evidence available here, so treat both as the supplier's own published claim rather than a measured result.

Questions to Ask Before You Switch

• What is included in the headline price, and what costs extra? Ask specifically about call minutes, handsets, number porting fees and any setup charge.
• Who is responsible for the migration and number porting, and what happens if a number fails to port before the switch-off date?
• What is the minimum contract term, and what does it cost to add or remove a user partway through?
• For Gamma Horizon specifically, is the partner Gamma-accredited, and what is their own support response time, since Gamma itself does not deal with end users directly?
• For 3CX, who hosts the system if you choose the self-hosted or private cloud route, and who is responsible for patching and security updates?
• For RingCentral, does the plan you are quoted include video, call recording and the integrations you actually use, or only the Essentials tier's stripped-down feature set?
• What happens to your existing analogue line and number if you do nothing before 31 January 2027?

Editorial Analysis

None of the three systems is a bad choice for a UK small business coming off analogue lines, but they suit different offices. A business with an existing IT relationship, whether an in-house person or a managed provider, is generally best placed to take advantage of 3CX's low per-extension cost, because someone still has to configure it, choose a host, and set up a SIP trunk for calls. An office with no appetite for any of that is often better served by Gamma Horizon, where a single accredited partner takes on the configuration, hosting, calls and support in one relationship, in exchange for a per-user price that includes everything.

RingCentral earns its higher price through breadth: video meetings, a large integrations marketplace and AI features across every plan. For an office that already relies on Microsoft 365 or a CRM platform, that breadth can be worth paying for. For an office that only wants staff to make and receive calls reliably, RingCentral's Standard plan at £19.99 a user a month is a lot to pay for features that will go unused, and the cheaper Essentials plan gives up video and call recording to get there.

The deadline itself should not be the deciding factor between these three, since all of them are IP-based and none depends on Openreach's copper network. What the deadline does is remove the option of doing nothing, and it puts a rising cost on delay through Openreach's own wholesale price increases.

Sources

• Wholesale Line Rental (WLR) Withdrawal, Openreach
• Openreach Warn 1.5 million UK Analogue Phone Lines Yet to Make Digital Switch, ISPreview
• Telecoms Modernisation, non-voluntary migration checklist, GOV.UK
• PBX Prices, Business Phone System Pricing, 3CX
• Now Available, 3CX Basic Edition and 4SC Basic Free, 3CX
• 3CX Pricing UK, Transparent 3CX Licence Costs, Clarion Communications
• Horizon Contact, Cloud Contact Centre, Gamma
• Gamma Horizon Pricing, T2K VoIP
• VoIP Phone System Vendor Comparison, Amvia
• RingCentral UK AI Communications Platform Plans and Pricing, RingCentral
• RingCentral Phone System Review, ExpertSure
• Help Guide for VoIP Phone Systems for UK Small Businesses, Compare the Cloud
• 3CX Features List, 3CX