VoIP & Unified Communications UK | Hosted Phone

Traditional ISDN and PSTN telephone systems are being permanently switched off by BT in December 2027. Every UK business still relying on analogue lines or ISDN circuits has no choice but to migrate before the deadline. This is not a voluntary upgrade — it is a mandatory change affecting every organisation in the country. Many network providers have already begun withdrawing ISDN products, leaving some businesses unable to renew or expand their existing setups. The businesses that act now, rather than waiting until the deadline approaches, will have significantly more choice, more time to plan, and access to better pricing.

Beyond the mandatory switch, hosted VoIP delivers tangible advantages that on-premise phone systems simply cannot match. Monthly costs fall dramatically when you eliminate hardware maintenance, line rental and per-minute call charges. Users can make and receive calls from any device — desk phone, laptop or mobile — from any location. New users can be added in minutes rather than requiring an engineer visit. Features such as call recording, auto-attendants, voicemail-to-email and Microsoft Teams integration are included as standard. Vertex9 migrates businesses to cloud voice ahead of the deadline, managing every step of the process with zero disruption to your operations.

Our Communications Services

End-to-end hosted voice and unified communications, from initial audit through to ongoing support — all managed by Vertex9.

Hosted VoIP (Cloud PBX)

A fully managed cloud-based phone system with no on-premise hardware to maintain. Your PBX lives in the cloud, scales instantly as you grow, and works from any internet-connected device. Add new users in minutes, not weeks. Features include voicemail, call forwarding, conference calling and call analytics — all included as standard.

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Microsoft Teams Voice

Use Microsoft Teams as your full business phone system via Direct Routing. Vertex9 connects your Teams environment to the public telephone network, enabling users to make and receive external calls directly within Teams. One platform for chat, video calls, file sharing and voice — eliminating the need for a separate phone system entirely.

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Call Recording & Compliance

FCA-compliant call recording for regulated sectors including financial services, legal and healthcare. Recordings are stored securely in the cloud with configurable retention periods, search and replay functionality. Meets MiFID II, FCA COBS and other regulatory requirements. Accessible via a web portal with full audit trail logging.

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IVR & Hunt Groups

Professional auto-attendant menus guide callers to the right department or individual without requiring a receptionist. Hunt groups and ring groups distribute calls across teams intelligently — round-robin, simultaneous ring or sequential. Call queuing with on-hold music, position announcements and overflow routing ensure no call goes unanswered.

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Number Porting & Migration

Keep every existing telephone number when you migrate. Vertex9 manages the complete number porting process, liaising with your current provider and the new carrier on your behalf. We inventory all your existing numbers, handle the porting authorisation forms, coordinate the cut-over date and test every number on the new system before go-live.

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The PSTN Switch-Off: Why You Must Act Now

BT's decision to retire the public switched telephone network by December 2027 affects every business in the UK still using traditional voice lines.

In December 2027, BT Openreach will permanently decommission the Public Switched Telephone Network (PSTN) and ISDN (Integrated Services Digital Network) infrastructure that has underpinned UK telephone communications for decades. After this date, traditional analogue phone lines and ISDN circuits will simply cease to function. There is no extension, no workaround and no option to remain on the old network. Every business in the United Kingdom that has not migrated to a digital alternative — whether that is VoIP, SIP trunking or a cloud PBX solution — will lose telephone service entirely.

The migration is not something that can be left until the final months before the deadline. Many network operators have already withdrawn new ISDN products from sale and are declining to renew existing ISDN contracts on a like-for-like basis. Businesses attempting to expand their telephone capacity on ISDN circuits are finding this increasingly difficult or impossible. Lead times for number porting can extend to several weeks, and businesses with large numbers of lines, complex call flows or multi-site environments will need considerably longer to plan and execute a smooth migration.

Vertex9 is helping UK businesses of all sizes migrate ahead of the deadline. By planning and executing the migration now, your organisation avoids the risk of being rushed into a poor solution under time pressure, benefits from competitive pricing, and has time to properly design call flows, train staff and test the new system before it goes live. Our team handles every aspect of the migration — from initial audit and design through to number porting, hardware procurement (where required), configuration, testing and training.

The PSTN switch-off also represents an opportunity. Migrating to a hosted VoIP or cloud PBX solution is not simply a like-for-like replacement of your old phone system — it is an upgrade. Businesses that embrace the transition benefit from lower monthly costs, greater flexibility, richer features and a communications infrastructure that is genuinely fit for modern working practices, including remote and hybrid work.

Key PSTN Switch-Off Dates

Now: Many providers have stopped selling new ISDN lines and are declining renewals
Throughout 2025–2026: Openreach stop-sell extensions across all exchanges
December 2027: Full PSTN and ISDN switch-off — all analogue and ISDN lines cease to work

Do not wait — contact Vertex9 today to begin planning your migration.

Microsoft Teams as Your Business Phone System

For businesses already using Microsoft 365, Teams Direct Routing turns your existing platform into a complete phone system — no separate PBX required.

Microsoft Teams has become the central hub for collaboration in the modern workplace — but many businesses are still paying for a separate telephone system alongside it. Microsoft Teams Direct Routing eliminates that duplication. By connecting Teams to the public telephone network via a certified Session Border Controller (SBC), Vertex9 enables your users to make and receive external telephone calls directly within the Teams application they already use every day.

The result is a single unified platform for every form of business communication. Chat, video meetings, file sharing, internal calls and external PSTN calls all happen within Microsoft Teams. There is no need to switch between applications or maintain separate desk phones (though physical Teams-certified handsets are available for those who prefer them). Users can make calls from their laptop, their mobile Teams app or a desk phone — from the office, at home or anywhere with an internet connection.

Teams Direct Routing integrates natively with the Microsoft 365 calendar, so outbound calls can be made directly from Outlook contacts. Call history appears within Teams alongside your chat history. Voicemails transcribed to text land in your Teams inbox. The experience is genuinely seamless in a way that bolting a VoIP system onto Teams via third-party apps simply cannot replicate.

From a cost perspective, Teams Direct Routing is typically the most economical option for businesses already paying for Microsoft 365 licences. Eliminating the separate PBX contract, hardware maintenance and associated line rentals often delivers savings of 30–50% on monthly communications spend. Vertex9 handles the full implementation — SBC configuration, Teams Phone licence assignment, call routing design, number porting and user training. Explore our Microsoft 365 managed services to understand the full scope of how we manage the M365 platform for UK businesses.

Benefits of Teams Direct Routing

One platform for chat, video, file sharing and voice calls
Native integration with Microsoft 365 calendar and Outlook contacts
Make and receive calls from any device — PC, Mac, iOS or Android
Significant cost saving versus maintaining a separate phone system
Auto-attendant and call queue features included
No on-premise hardware to manage or maintain
Scales instantly as your team grows or changes

How Our VoIP Migration Works

A structured four-stage process ensures a smooth transition with no disruption to your business communications.

01

Assessment

We begin with a thorough audit of your current telephone infrastructure — number inventory, call volumes, peak traffic periods, existing hardware, line contracts and any special requirements such as alarm lines, fax machines or door entry systems. We review your broadband connectivity and assess whether network upgrades are needed to support VoIP quality. This assessment forms the foundation for everything that follows and is provided free of charge.

02

Design

Using the information gathered during assessment, Vertex9 designs your new communications environment. This covers call flow design — how incoming calls are routed, IVR menu structures, hunt group configurations, ring strategies and overflow rules. We design the system around how your business actually operates, not around the limitations of the technology. You review and approve the design before any configuration work begins.

03

Deploy

With the design approved, Vertex9 provisions the cloud phone system and begins the number porting process with your existing carrier. Any new hardware — IP handsets, headsets, conference phones — is procured, pre-configured and delivered ready to plug in. We run parallel testing before the cut-over date, ensuring every number, call flow and feature works exactly as designed. The go-live switch is performed at a time that minimises any risk to your business, with Vertex9 engineers on hand throughout.

04

Support

After go-live, Vertex9 provides 24/7 ongoing managed support for your communications platform. Moves, additions and changes — adding new users, updating call flows, adjusting ring groups — are handled by our team, typically within hours. We monitor call quality, system health and usage analytics proactively, identifying and resolving issues before they affect your users. Your communications infrastructure becomes a managed service you never have to worry about. We also integrate with our network support team to ensure end-to-end performance.

Frequently Asked Questions About VoIP

Answers to the questions UK businesses most commonly ask before migrating to hosted VoIP.

What is VoIP and how does it work?

Voice over IP (VoIP) converts your voice into digital data packets that are transmitted over the internet rather than through a traditional copper telephone line. When you speak into a VoIP handset, headset or softphone application, your voice is encoded, compressed and sent as data across your internet connection to the recipient. At the other end, the data is decoded and converted back into audio — indistinguishable from a regular phone call. Because VoIP uses the internet rather than a physical telephone line, calls can be made from any internet-connected device and from any location, making it ideal for remote and hybrid working environments.

Will call quality be as good as a traditional phone?

Yes — and in many cases, VoIP call quality is noticeably better than a traditional PSTN line. Modern VoIP systems use high-definition audio codecs that deliver significantly clearer voice quality than the narrow-band audio of traditional telephony. The key requirement is a reliable broadband connection with sufficient bandwidth and, crucially, properly configured Quality of Service (QoS) settings on your network. QoS prioritises voice traffic over other data, preventing call quality degradation when the network is busy. Vertex9 assesses your broadband connection and network configuration as part of the pre-migration audit to ensure quality standards are met before a single call is made on the new system.

Can we keep our existing phone numbers?

Yes. Keeping your existing telephone numbers is standard practice when migrating to VoIP. The process is called number porting, and Vertex9 manages it entirely on your behalf. We inventory all your current numbers, submit the porting authorisation request to your existing provider and coordinate the transfer to the new VoIP platform. The porting process typically takes two to four weeks depending on the number of lines and your current carrier. Throughout the process, your existing numbers remain active and calls continue to be received without interruption. We test all ported numbers on the new system before the final cut-over, so there is no risk of losing incoming calls.

What happens if our internet goes down?

Resilience against internet outages is built into the way Vertex9 designs VoIP deployments. Calls can be automatically diverted to mobile numbers, an alternative office location, or an answering service in the event of a broadband failure. For businesses where communications are business-critical, we recommend implementing a secondary broadband connection — such as a 4G/5G bonded connection — as automatic failover. The VoIP system detects a primary circuit failure and switches to the backup within seconds, maintaining call continuity. Vertex9 can also advise on our network support services to ensure the underlying connectivity supporting your VoIP system is as resilient as possible.

How long does VoIP migration take?

A typical VoIP migration for a small to medium-sized business takes two to four weeks from initial assessment through to go-live, including number porting, device configuration and user training. The timeline is primarily driven by the number porting process, which is controlled by your existing telephone provider and subject to regulatory lead times. Complex environments — businesses with large number portfolios, multiple sites, or specialist requirements such as contact centre queuing or FCA-compliant call recording — may require additional time for design and testing. Vertex9 provides a detailed project timeline at the start of every engagement so you know exactly what to expect and when.

Get a Free Communications Review

Whether you need to migrate ahead of the 2027 PSTN switch-off, reduce your monthly phone bills, or consolidate communications onto Microsoft Teams, Vertex9 can help. Our free comms review covers your current setup, future requirements and a clear migration roadmap — with no obligation to proceed.

Request a Free Review Call 020 3633 9124

Speak to a communications specialist today. No obligation. No pushy sales calls.

VoIP & Unified Communications for UK Businesses