How To Set Up a VoIP Phone System in the UK

Setting up a VoIP phone system is easier than it sounds to the uninitiated, as long as you do things in the right order.

This guide gives UK businesses an exact step-by-step path from first network check to live call flows and 999 readiness, so you can launch faster, avoid redoing work, and get ahead of the UK’s landline switch-off in January 2027.

1. Test Your Network Connection

As the traditional phone PSTN phone network will be discontinued in 2027 in a process known as the Big Switch Off, most businesses will be turning to VoIP systems as a replacement. VoIP traffic is sent across the internet, so ensuring your network is up to the task is essential.

The bandwidth requirements for a VoIP phone installation are quite modest: typically around 100 kbps for both upload and download per line. Given that most internet service providers in the UK offer business plans with gigabit speeds, your existing connection is likely sufficient. However, be mindful of home connections like some DSL lines, which may have slower upload speeds.

Stability is key for VoIP. Factors like jitter and packet loss, which are common issues with unstable connections, can significantly affect call quality. Opt for a wired internet connection, such as fibre or cable, over less stable alternatives like 5G Wi-Fi.

Your network hardware also plays a pivotal role. If your router or network struggles with peak traffic, this could result in poor audio quality or dropped calls. While Wi-Fi can suffice, a wired connection is always the more reliable choice.

Conducting a VoIP speed test is a practical step to assess your network’s readiness. This test simulates the demands of a VoIP system, helping you identify any potential issues. RingCentral and T2K are two examples of free online VoIP speed tests.

Additionally, consider configuring quality of service (QoS) settings in your router, if available. By prioritising VoIP packets, you ensure that voice traffic takes precedence over less critical data such as streaming services, thus reducing latency and packet loss. This setup guarantees that your VoIP calls remain clear and uninterrupted, even during periods of high network usage.

2. Choose a VoIP Provider

It’s important to evaluate the features offered by every potential VoIP provider and ensure they align with your specific needs. For instance, features like customisable voicemail greetings could be invaluable if you manage a customer service team. On the other hand, if your team often works remotely, a provider offering browser-based meeting access might be more suitable.

Cost is undoubtedly a significant factor in your decision. VoIP systems typically have low initial costs and no installation fees, however advanced phone system features like call routing, auto-attendants, and video conferencing can increase the overall expense. It’s best to look for a provider that offers the flexibility to tailor features to your requirements, providing a cost-effective, scalable and customisable solution that doesn’t compromise functionality (and in fact, meets your evolving needs).

Customer support quality is another key consideration. If your operations span multiple countries, look for providers offering global, round-the-clock support, complete with dedicated resources and live chat options.

You’ll want to confirm the provider meets Ofcom General Condition A3: free access to 999/112 and reliable caller location information for fixed services. Ofcom fined a UK provider in 2025 for issues related to this, so it’s important to thoroughly check this out. Also ask how they capture and maintain addresses for each site/endpoint, and consider power cuts and how that VoIP helps with this in emergencies.

Providers that support integrations with existing business tools, such as customer relationship management (CRM) systems and analytics, can offer additional value, potentially saving costs in other areas.

If your office already has a PBX phone system, which is a private phone system, choosing a SIP (Session Initiation Protocol) provider can be a smart move to grow your system. The difference between SIP and VoIP is that SIP trunking lets you send all types of data, like voice and video, over one internet-based network instead of having separate networks for each. This approach reduces costs and simplifies maintenance, as it replaces complex hardware with user-friendly software solutions.

Hosted cloud PBX vs SIP trunks vs Microsoft Teams Phone

• Hosted cloud PBX (UCaaS): Fastest rollout and per-user pricing; good when you want a full suite (IVR, queues, analytics) without running your own PBX.
• SIP trunks for an existing PBX: Keep your current IP-PBX and replace legacy lines with internet-based channels; suits sites with established call flows or hardware you’re not ready to retire.
• Microsoft Teams Phone: Keep Teams as your softphone and add PSTN via:
  • Operator Connect: pick a Microsoft-approved carrier in the Teams Admin Center; simpler carrier management.
  • Direct Routing: bring your own carrier via a certified SBC for maximum control and complex routing; can be mixed with Operator Connect.

How to choose?

• Go cloud PBX if you want plug-and-play voice with rich features.
• Go SIP trunks if you’re extending a PBX you already own.
• Go Teams (Operator Connect) for simplicity inside Microsoft 365 or Teams (Direct Routing) when you need BYO carrier/global reach or custom policies.

3. Purchase VoIP Hardware

Due to the widespread adoption of VoIP in businesses, you have a wealth of state-of-the-art options to choose from. Choosing the right VoIP hardware depends on your specific business needs and preferences.

Whether you opt for high-quality VoIP phones, adaptable headsets, analogue adapters, or software-based softphones, each option offers unique benefits that enhance your team’s communication efficiency.

High-Quality VoIP Phones

For optimal call quality, consider investing in high-end VoIP desk phones. These phones are designed for crystal-clear audio, essential for professional interactions. If your requirements are more basic, there are also budget-friendly alternatives that cater to simple call-making and receiving functions.

VoIP Headsets: Enhancing Mobility

To enhance mobility and multitasking capabilities, VoIP headsets are an excellent addition. They enable your team members to move freely while on calls so they can access customer information, interact with colleagues, or update records in a CRM system without interruption.

Retain Your Existing Phones with Adapters

If you’re keen on using your current office phones, an analogue telephone adapter (ATA) can make this possible. This device bridges your analogue phones with your VoIP network by digitising the analogue signals. This option eliminates the need for staff retraining, as they can continue using familiar equipment.

Softphones: A Cost-Effective Alternative

Softphones offer a budget-friendly alternative to traditional hardware. These are software-based phone systems that can be installed on computers or smartphones. Since VoIP operates over the internet, dedicated hardware isn’t a necessity. This means you can bypass some of the traditional office phone installation steps. Read about the best softphone apps on our page.

A softphone functions like a standard phone, allowing you to make and receive calls over any telephone or mobile network. All you need for effective call handling is a quality USB or Bluetooth headset.

Most laptops have built-in microphones and speakers, enabling immediate phone usage. Additionally, mobile VoIP is readily available for Android and iOS devices, allowing your team to manage business calls on their smartphones.

4. Connect the VoIP Equipment

Connecting your VoIP equipment is straightforward but varies slightly based on the hardware and network setup. Here’s how to connect a VoIP phone:

Connecting VoIP Desk Phones with Power over Ethernet (PoE)

For phones supporting PoE, the setup is simple, as the network cable carries both data and power.

1. Connect your phone to a PoE-enabled switch or router using an Ethernet cable. Ensure the cable length is within the maximum recommended 328 feet for twisted pair cables.
2. The phone should power up upon connection and automatically establish a connection with your VoIP provider.

Setting Up VoIP Desk Phones without PoE

If your phones don’t support PoE, you must power them separately and connect them to your network.

1. Plug the AC adapter into the outlet and then the phone or handset base.
2. Use a CAT5e or CAT6 cable to connect the IP phone to your network switch or router.
3. After connecting, wait for the phone to initialise. Once it’s ready, check for a dial tone to confirm connectivity.

Setting Up VoIP Headsets with Electronic Hook Switch (EHS)

Modern wireless headsets often support one-touch answering, a feature that requires an EHS cable for setup.

1. Connect the headset’s base unit to a power outlet.
2. Attach one end of the EHS cable to the base unit and the other to the phone using the designated headset and EHS ports. Follow specific instructions from the EHS manual for detailed steps.
3. Wear the headset and press the call control button to check the connection.

Connecting Wired Headsets with Phone Jacks

For wired headsets using regular phone jacks, the process is straightforward.

1. Plug the headset’s cable jack into the headset port on the desk phone, often marked with a small icon.
2. Put on the headset and press the call control button to check for a dial tone.
3. Make a test call to confirm the volume and call quality. If necessary, use an amplifier to increase the headset volume.

5. Configure the VoIP system

Once you’ve connected your VoIP equipment, there are several settings you may want to configure. Each VoIP system offers different features and will be set up differently, so consult the manual or documentation for this step. Here’s a list of some of the most common configuration steps you might need to take:

• Assign direct phone numbers or extensions to each VoIP phone. This may involve mapping each phone to a specific department or individual in your organisation.
• Set up network parameters like IP addresses, subnet masks, and gateways according to your network’s configuration.
• Configure voicemail boxes for each extension, including greetings, password settings, and voicemail-to-email options.
• Create rules for routing incoming calls, such as time-based routing, hunt groups, or forwarding calls to mobile phones or other numbers when unavailable.
• If your system supports interactive voice response (IVR), configure the voice menu to guide callers to the appropriate department or extension.
• Configure the integration with your CRM software or other business applications for features like screen pops and call logging.
• Enable and configure options for conference calls, including setting up dedicated conference bridges if required.
• Adjust features like call hold, transfer, park, and pick-up according to your business needs.
• Implement security protocols such as SIP security, VPNs, and firewalls to protect against unauthorised access and ensure data privacy.
• Ensure that your VoIP devices are running the latest firmware and software versions for optimal performance and security.

6. Test the VoIP System

Once you’ve set up your VoIP system, thoroughly test it to ensure everything functions correctly. A comprehensive test will help you identify and rectify any issues before the system goes live for business use.

Don’t limit your testing to just one or two calls. Make several calls at different times and under various network conditions to thoroughly assess the system. If possible, get feedback from the people on the other end of your test calls. Their input can provide valuable insights into the user experience from an external perspective.

Here’s what to focus on during testing:

• Clarity: Ensure that the audio quality during calls is crystal clear. Listen for any static, background noise, or signs of poor quality.
• Consistency: Check if the audio quality remains consistent throughout the call duration.
• Delay: Monitor for any noticeable delays between speaking and the other party hearing your voice. Significant latency can disrupt the flow of conversation.
• Call Stability: Make sure calls don’t drop unexpectedly. Some firewalls might cause calls to drop after a specific time, so test for an extended period, ideally 15-30 minutes, to assess stability.
• Network Congestion: Test the system during peak network usage. High network traffic can lead to various issues like dropped calls or choppy audio. This test is crucial to understand how your VoIP system performs under stress.

7. Train Staff

While VoIP technology offers advanced features, its success hinges on your team’s ability to use these effectively. Organise VoIP training sessions soon after installation. Break down the staff into small groups for more focused and interactive training.

Start with an overview of the VoIP system, highlighting its benefits and differences from traditional phone systems. Emphasise key features like voicemail-to-email, call forwarding, and conferencing.

Use a step-by-step approach to demonstrate basic functions such as making and receiving calls, transferring calls, setting up voicemail, and using the directory. Encourage staff to practise these functions during the session.

Provide reference guides or cheat sheets for quick reference. Include FAQs, troubleshooting tips, and contact information for technical support.

Encourage questions during training and have an interactive Q&A session to address specific concerns or scenarios. Schedule follow-up sessions after a few weeks to cover advanced features or updates and address any issues encountered.