How to Move Your VoIP Phone System to a New Office

Relocating your office is a major undertaking for any UK business, and your phone system is one of the most critical pieces of infrastructure to get right. A poorly planned VoIP migration can leave your team without reliable communications for days or even weeks — missed calls from clients, dropped conversations with suppliers, and frustrated staff who cannot do their jobs properly.

The good news is that modern VoIP and cloud telephony systems are inherently more portable than the old ISDN lines and PBX boxes they replaced. With the right planning, you can move your entire phone system to a new office in Bristol, Glasgow, Cardiff, or anywhere else in the UK with minimal disruption. This guide walks you through every step of the process, from initial planning through to post-move quality assurance.

With the PSTN switch-off well underway across the UK — BT Openreach is retiring traditional phone lines entirely by January 2027 — now is also an ideal time to evaluate whether your current VoIP setup is fit for purpose or whether the office move presents an opportunity to upgrade.

Assessing Your Current Phone System

Before you start planning the move, you need a thorough understanding of what you currently have. This assessment will determine whether you can simply relocate your existing system or whether the move is an opportunity to modernise.

Start by documenting your current setup. Are you running an on-premises IP PBX such as a Cisco Unified Communications Manager, an Avaya IP Office, or a 3CX installation? Or are you using a cloud-hosted VoIP service like Microsoft Teams Phone, RingCentral, 8x8, or Vonage Business? The distinction is crucial because it fundamentally changes the migration approach.

For on-premises systems, you will need to physically relocate the PBX hardware, which requires careful decommissioning at the old site and recommissioning at the new one. For cloud-hosted systems, the migration is significantly simpler — your phone system lives in the cloud, so you only need to ensure the new office has adequate network infrastructure and that your handsets are moved and reconnected.

Network Requirements: Getting the Foundation Right

VoIP quality is entirely dependent on your network infrastructure. Unlike data traffic, which can tolerate brief delays and retransmissions, voice traffic demands consistent, low-latency connectivity. A network that handles email and web browsing perfectly well may struggle with VoIP if it has not been properly configured.

At your new office, you need to ensure the network meets several critical requirements. First, bandwidth: each concurrent VoIP call requires approximately 100 Kbps of dedicated bandwidth in each direction. For a 50-person office where a maximum of 30 people might be on calls simultaneously, you need at least 3 Mbps of dedicated bandwidth for voice alone, on top of your regular data requirements. Most UK business broadband and leased line connections comfortably exceed this, but it is essential to verify.

Second, Quality of Service (QoS). This is the single most important technical configuration for VoIP and the one most commonly overlooked. QoS policies on your network switches and firewall prioritise voice traffic over other data, ensuring that a large file download or a Windows Update never degrades call quality. Without QoS, your calls will sound fine when the network is quiet but may suffer from jitter, latency, and packet loss during busy periods.

SIP Trunks and Number Porting

Your phone numbers are a critical business asset. Clients, suppliers, and partners know your numbers, they appear on your marketing materials, and they may have been associated with your business for years. Losing them during an office move is unacceptable, so number porting must be planned carefully.

If you are using SIP trunks (the VoIP equivalent of phone lines), your numbers are typically tied to your SIP trunk provider rather than a physical location. This means porting your numbers during an office move is usually a straightforward administrative process. However, it requires coordination with your provider and should be initiated at least four to six weeks before your move date.

For businesses still using geographic numbers (those with area codes like 0121 for Birmingham, 0161 for Manchester, or 0131 for Edinburgh), Ofcom regulations allow you to port these numbers to a VoIP provider regardless of your physical location. This means a business moving from central London to Reading can keep its 020 numbers. A company relocating from Leeds to Newcastle can retain its 0113 numbers. The number porting process in the UK typically takes 7 to 10 working days, though complex ports involving multiple ranges can take longer.

Number Type	Portability	Typical Porting Time	Key Considerations
Geographic (01/02)	Fully portable to any UK VoIP provider	7–10 working days	Can be kept regardless of physical location
Non-geographic (03)	Fully portable	7–10 working days	Location-independent by design
Freephone (0800/0808)	Fully portable	10–15 working days	Ensure VoIP provider supports inbound freephone
Mobile (07)	Fully portable	1–3 working days	If using mobile integration with VoIP
International DDIs	Varies by country	2–6 weeks	Check provider capability per country

Handset Provisioning and Deployment

The physical handsets on your desks need to be properly provisioned for your new network environment. How you handle this depends on whether you are keeping your existing handsets or upgrading as part of the move.

If you are keeping existing handsets, they will need to be factory reset and reprovisioned with the new network settings at the new office. Most enterprise VoIP handsets from manufacturers like Yealink, Poly (formerly Polycom), and Cisco support zero-touch provisioning — where the handset automatically downloads its configuration from a provisioning server when it connects to the network. This dramatically simplifies deployment at the new site.

If you are upgrading handsets, the office move is the ideal time to do it. Modern VoIP handsets offer features like colour displays, Bluetooth connectivity for wireless headsets, built-in Wi-Fi for flexible placement, and native integration with platforms like Microsoft Teams. For a typical UK SME, budget between £80 and £250 per handset depending on features and brand. Conference phones for meeting rooms typically cost £300 to £800.

Microsoft Teams Phone Integration

An increasing number of UK businesses are consolidating their communications onto Microsoft Teams, using it not just for internal chat and video meetings but as a full replacement for their traditional phone system. If you are already using Microsoft 365, integrating Teams Phone into your office move can simplify your telephony setup significantly.

Microsoft Teams Phone (formerly Teams Calling) allows your staff to make and receive external calls directly within the Teams application on their computers, mobile phones, or certified desk phones. There are two primary approaches to enabling external calling in Teams: Microsoft Calling Plans, where Microsoft provides the SIP trunks and phone numbers directly, and Direct Routing (or the newer Operator Connect), where you connect Teams to a third-party SIP trunk provider.

For most UK SMEs, Operator Connect offers the best balance of simplicity and flexibility. It allows you to keep your existing UK phone numbers with a provider like Gamma, BT Wholesale, or Virgin Media Business, whilst routing all calls through the Teams interface. Your staff get a unified communications experience — chat, video, and voice all in one application — and you get the flexibility to choose your preferred UK carrier.

Planning the Migration Timeline

A successful VoIP migration requires meticulous planning. Start the process at least eight weeks before your move date, and work backwards from the day you need the phones operational at the new site.

During weeks one and two, conduct a full audit of your current phone system. Document every phone number, extension, call route, auto-attendant greeting, voicemail box, call group, and hunt group. Identify any integrations with CRM systems, call recording platforms, or contact centre software. This audit becomes your migration specification — it defines exactly what needs to be replicated at the new site.

During weeks three and four, work with your VoIP provider or MSP to design the phone system configuration for the new office. This includes VLAN configuration for voice traffic, QoS policies on switches and firewall, DHCP scopes for handsets, and any changes to call routing or auto-attendant menus. If you are porting numbers, initiate the process now.

During weeks five and six, install and configure the network infrastructure at the new office. Test the internet connection, configure VLANs and QoS, and run VoIP quality tests to ensure the network can support the required call volume. Set up any new handsets and test them against the provisioning server.

During the final two weeks, conduct a full parallel test. If possible, set up a few handsets at the new site and route a subset of calls to verify everything works. Plan the cutover carefully — ideally for a Friday evening or weekend to minimise business disruption. Have a rollback plan in case of unexpected issues.

Testing Call Quality Post-Move

Once you are operational at the new office, thorough testing is essential. Do not assume everything is working just because calls connect — subtle quality issues can lurk beneath the surface and only become apparent under load.

Test every call scenario: inbound calls to main numbers and DDIs, outbound calls to landlines and mobiles, internal extension-to-extension calls, conference calls with multiple participants, calls during peak network usage, transfers between extensions, voicemail recording and playback, and auto-attendant routing. Pay particular attention to call quality during busy periods — the first Monday morning after the move is the real test, when everyone is on calls, downloading emails, and syncing files simultaneously.

Common Pitfalls and How to Avoid Them

Having supported dozens of UK businesses through office relocations, we have seen the same mistakes repeated time and again. Here are the most common pitfalls and how to avoid them.

Not testing the internet connection early enough. Many businesses assume their new leased line or broadband will be installed and working by move day. In reality, UK ISP installations frequently overrun. Order your internet connection for the new office at least 12 weeks in advance, and have a 4G/5G failover ready as a contingency.

Forgetting about analogue devices. Fax machines, door entry systems, alarm lines, lift emergency phones, and franking machines often use analogue phone lines that are separate from your VoIP system. These need analogue telephone adapters (ATAs) to work over VoIP, and they must be tested thoroughly before the move.

Underestimating switch port density. VoIP handsets need network ports. If your handsets do not have a built-in network pass-through port, you will need double the number of switch ports — one for the PC and one for the phone at each desk. Plan your switch capacity accordingly.

Neglecting Power over Ethernet. Most modern IP handsets are powered via PoE (Power over Ethernet), which means your network switches need to support PoE and have sufficient power budget to run all connected handsets. A 48-port PoE+ switch typically provides 740W, which is enough for approximately 35 to 40 handsets at 15W each. Verify your PoE budget before ordering switches.

Post-Move Optimisation

The migration does not end on move day. Plan for a two-week optimisation period where you actively monitor call quality metrics, gather user feedback, and fine-tune the configuration. Common post-move adjustments include tweaking QoS priorities based on real traffic patterns, adjusting auto-attendant greetings and routing for the new office layout, reconfiguring call groups and hunt groups to reflect new seating arrangements, updating contact directories and speed dials, and training staff on any new handset features or softphone applications.

Use your VoIP platform's call analytics to monitor key quality metrics during this period. Most modern platforms provide dashboards showing mean opinion score (MOS), jitter, latency, and packet loss per call. Any call with a MOS below 3.5 should be investigated, and patterns of poor quality at specific times or for specific users can indicate network issues that need addressing.

Your MSP or VoIP provider should be closely involved during this optimisation period, ready to make configuration changes and troubleshoot any issues that arise. Consider scheduling a formal review two weeks after the move to assess overall system performance and address any outstanding concerns.