VoIP FAQ: 25 Questions UK Businesses Ask Before Switching

Last updated: April 2026

Switching to VoIP is one of the best decisions a small business can make. Lower costs, better features, more flexibility, and future-proofing ahead of the PSTN switch-off in January 2027.

But if you have never used VoIP before, you probably have questions. Fair enough. You are changing the way your entire business communicates. You want to know it will work, what it will cost, and whether you will lose your phone number in the process.

At Compare The Networks, we have helped over 2,000 UK businesses switch to VoIP since 2008. We hear the same questions every day. This page answers the 25 most common ones, grouped by topic so you can find what you need quickly.

If your question is not here, get in touch and we will answer it personally.

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VoIP Basics

1. What is VoIP and how does it work?

VoIP (Voice over Internet Protocol) converts your voice into digital data and sends it over your internet connection instead of traditional copper phone lines. When you speak into a VoIP phone, your voice is broken into tiny data packets, sent across the internet to the person you are calling, and reassembled into audio at the other end. The whole process happens in milliseconds, so the call sounds just like a normal phone call.

You can use VoIP through dedicated desk phones (IP phones), a softphone app on your computer, or a mobile app on your smartphone.

2. Do I need special phones for VoIP?

You do not need special phones, but dedicated IP phones give the best experience. You have three options:

• IP desk phones from brands like Yealink, Snom, Fanvil, Grandstream, Cisco, Polycom, Panasonic, or Gigaset. These typically cost from GBP50 to GBP150 per handset to buy, or GBP3 to GBP5 per month to lease.
• Softphone apps that run on your existing computer (Windows or Mac) using a headset.
• Mobile apps that turn your smartphone into a VoIP extension.

Most businesses use a mix of all three depending on what suits each team member.

3. What is 3CX and why do people recommend it?

3CX is one of the most popular VoIP phone system platforms in the UK. It is a software-based PBX that can be hosted in the cloud or on your own server. Businesses like it because it offers a full set of features (auto-attendant, call recording, video conferencing, live chat, CRM integration) with a clean web-based interface that is relatively easy to manage.

It also has good mobile and desktop apps. We supply and support 3CX systems for many of our clients. It works well for businesses from 5 to 500+ users and integrates with popular CRMs and Microsoft 365.

4. What if I only have one or two staff? Is VoIP worth it?

Absolutely. For very small businesses, a virtual landline or basic VoIP plan from around GBP6+VAT per user per month gives you a professional business number, voicemail to email, call forwarding to your mobile, and a mobile app.

You do not even need a desk phone. The mobile app on your smartphone does the job. It means clients call your business number, not your personal mobile. You can set business hours so calls go to voicemail outside working hours. And if you grow, you can add extensions and features without changing systems.

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Costs and Contracts

5. How much does VoIP cost for a small business?

VoIP pricing works on a per-user monthly basis. Here is what you can expect:

Most small businesses find that a standard tier plan covers everything they need. Get a tailored quote based on your exact requirements.

6. Are there hidden costs with VoIP?

Reputable providers are transparent about pricing, but there are costs beyond the per-user fee to be aware of:

• Hardware: Desk phones cost GBP50 to GBP150 each to buy, or GBP3 to GBP5 per month to lease
• Number porting: Sometimes charged, though many providers include this free
• International calls: Usually charged per minute on top of your plan
• Call recording storage: Some providers charge beyond a certain amount of storage
• Broadband upgrade: If your current connection is not up to scratch

We always give a fully itemised quote with no surprises.

7. Am I locked into a long contract?

It depends on the provider. Some offer month-to-month rolling contracts with no lock-in. Others offer 12 or 24 month contracts at a lower per-user rate. As a general rule, monthly contracts cost 10 to 20 percent more than annual commitments.

We recommend starting with a 12 month contract for the best balance of price and flexibility. Avoid 36 month contracts unless you are absolutely certain. When you get a quote through us, we will always make the contract terms clear upfront.

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Setup and Migration

8. How long does it take to set up VoIP?

A straightforward setup for a small business (under 20 users) can be up and running in 3 to 5 working days. That includes configuring extensions, setting up call routing, programming phones, and testing.

If you are porting existing phone numbers, that adds 10 to 15 working days for the number transfer. But you can start using temporary numbers immediately while the port processes. Larger or more complex setups with multiple sites or CRM integrations may take 2 to 4 weeks.

9. Can I keep my existing phone number?

Yes. You can port (transfer) your existing landline, virtual landline, or VoIP number to your new provider. The process takes 10 to 15 working days for standard UK geographic numbers.

During the porting period, your old number continues to work normally, so you do not miss any calls. The key is making sure the information on the port request matches exactly what your current provider has on file. We handle the porting process for you and chase any delays.

10. What broadband do I need for VoIP?

Each simultaneous VoIP call uses approximately 100Kbps of upload bandwidth. Here is what you need:

Standard FTTC broadband with 80/20 speeds is fine for most small businesses. We recommend Sky Business Broadband SOGEA 80/20 at GBP35+VAT specifically because the 20Mbps upload is well suited to VoIP. If your current broadband does not meet these requirements, we can sort a better connection before setting up your phones.

11. Will VoIP work over WiFi?

VoIP can work over WiFi, but wired ethernet connections are always better for desk phones. WiFi introduces variable latency and potential interference that can cause choppy audio or dropped calls.

For desk phones, always use ethernet cables. For softphone apps on laptops, use 5GHz WiFi rather than 2.4GHz. Mobile VoIP apps work well over WiFi for occasional use. If you rely heavily on WiFi for VoIP, invest in a business-grade access point with QoS that prioritises voice traffic.

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Features

12. What features come with a business VoIP system?

Modern VoIP systems include features that would cost thousands on a traditional PBX:

• Auto-attendant (press 1 for sales, 2 for support)
• Voicemail to email
• Call transfer and forwarding
• Call recording
• Ring groups (multiple phones ring for the same call)
• On-hold music and messages
• Direct dial numbers (DDI) for each staff member
• Mobile and desktop apps
• Call history and basic reporting
• Conference calling

Premium plans add CRM integration, advanced call analytics, call queuing, wallboards for contact centres, and whisper/barge features for training. Read our complete VoIP guide for a full features breakdown.

13. What is call recording and is it legal?

Call recording lets you automatically or manually record phone calls and store them for playback later. It is legal in the UK to record business calls, but you must comply with GDPR.

If you record calls, you should tell the caller at the start of the call (the standard "calls may be recorded for training and quality purposes" announcement). Recordings must be stored securely and only accessed by authorised people. You should have a data retention policy stating how long recordings are kept. Most VoIP systems include call recording on standard or premium plans.

14. What is an auto-attendant and do I need one?

An auto-attendant is the automated greeting that answers your phone and directs callers to the right department or person. For businesses with more than one department or more than a few staff members, an auto-attendant is genuinely useful.

It means callers get through to the right person without a receptionist, and it makes a small business sound professional and established. Most VoIP plans include auto-attendant at no extra cost. Keep the menu simple though. Two or three options is plenty. Nobody wants to listen to seven options.

15. Can I use VoIP on my mobile phone?

Yes. Almost every business VoIP provider offers a mobile app (iOS and Android) that turns your smartphone into a full extension of your office phone system. You can make and receive calls using your business number, transfer calls to colleagues, access your voicemail, and see who is available.

Calls can come in over WiFi or mobile data (4G/5G). This is particularly useful for remote workers, staff who are frequently out of the office, and as a backup if your desk phone is unavailable. The mobile app uses your VoIP number as the caller ID, so clients see your business number, not your personal mobile number.

16. Can VoIP integrate with my CRM?

Yes. Most modern VoIP platforms integrate with popular CRMs including Salesforce, HubSpot, Zoho, and Microsoft Dynamics. The integration typically provides:

• Click-to-call: Click a phone number in your CRM to dial it
• Screen pops: The caller's CRM record appears on screen when they ring
• Automatic call logging: Calls are logged against the contact record
• Call recording linked to the CRM

3CX, for example, has built-in CRM integration modules for most major platforms.

17. How many phone numbers can I have?

As many as you need. With VoIP, you can have a main business number, direct dial numbers (DDIs) for each staff member, local numbers for different areas (a London 020 number, a Manchester 0161 number, etc.), and even international numbers.

Each number routes to wherever you want: a specific extension, a ring group, or an auto-attendant. DDIs typically cost GBP1 to GBP3 per month each. Geographic numbers for different areas are useful if you want a local presence in multiple cities without opening physical offices.

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Reliability and Security

18. What happens to my phones if the internet goes down?

If your internet connection drops, your VoIP desk phones will stop working because they rely on the internet to make and receive calls. However, this does not mean you miss calls.

VoIP systems can be configured to automatically forward incoming calls to your business mobile phones when the desk phones go offline. This failover happens within seconds. You can also use your VoIP mobile app over 4G or 5G data, which is independent of your office broadband.

For critical businesses, a small UPS (uninterruptible power supply, around GBP80 to GBP150) can keep your router running during short power cuts.

19. Is VoIP call quality as good as a traditional landline?

On a properly set up connection, VoIP call quality is equal to or better than a traditional landline. Modern VoIP uses HD audio codecs (like G.722 and Opus) that deliver wideband audio, meaning clearer, richer sound than the narrowband audio of traditional phone lines.

The key is having adequate broadband with sufficient upload speed, low latency, and low jitter. If those network requirements are met, you will not be able to tell the difference. HD VoIP calls between two VoIP users sound noticeably better than traditional calls. If you do experience quality issues, our VoIP troubleshooting guide covers every common problem and fix.

20. Can I make 999 emergency calls on VoIP?

Yes, but with an important caveat. VoIP providers are required by OFCOM to provide access to 999 and 112 emergency services. However, because VoIP numbers are not tied to a physical location the way traditional landlines are, the emergency services may not automatically know your location.

You should register your business address with your VoIP provider so that location information is passed to the emergency operator when you dial 999. If you use VoIP from a different location, the registered address may not match. For this reason, having a business mobile as a backup is sensible for emergency calls.

21. Is VoIP secure? Can calls be intercepted?

Modern VoIP systems support strong encryption. SRTP (Secure Real-time Transport Protocol) encrypts the audio of your calls, and TLS (Transport Layer Security) encrypts the signalling data. With both enabled, your VoIP calls are as secure as any other encrypted internet communication.

Make sure your provider supports and enables encryption by default. Beyond call encryption, standard security practices apply: use strong passwords for SIP accounts, keep phone firmware updated, and ensure your network firewall is properly configured.

22. Can I have VoIP across multiple office locations?

Yes, and this is one of VoIP's biggest strengths. Because VoIP runs over the internet, all your locations can share one phone system. Staff at different offices can transfer calls between sites as easily as transferring to the desk next door. You can have a single main number with extensions across all locations. Ring groups can include staff from multiple offices. And the management is centralised through one web portal.

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The PSTN Switch-Off

23. What is the PSTN switch-off and does it affect me?

The PSTN (Public Switched Telephone Network) is the traditional copper wire telephone network that has carried UK phone calls for over a century. Openreach is switching it off permanently, with the process completing in January 2027.

After that date, traditional analogue phone lines will stop working. If your business currently uses a standard landline, ISDN lines, or an older PBX system that connects via analogue lines, you will need to switch to VoIP before January 2027. If you are already on VoIP, the switch-off does not directly affect your phone system, though you should check that your broadband does not depend on the PSTN. Our PSTN switch-off guide has full details.

24. What happens if I do nothing before the PSTN switch-off?

If you still have a traditional analogue phone line when the PSTN is switched off in your area, your line will stop working. You will not be able to make or receive calls on that number.

Openreach is switching off exchanges area by area, with all exchanges completed by January 2027. Some areas have already been switched off. Rather than waiting until the last minute, we strongly recommend planning your move now. Porting numbers takes 10 to 15 working days, and if thousands of businesses leave it until the final months, there could be bottlenecks. Get a free quote now and avoid the rush.

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Choosing a Provider

25. How do I choose the right VoIP provider?

The right provider depends on your size, features needed, budget, and how much support you want. Key things to check:

This is exactly what we do at Compare The Networks. We compare VoIP providers across all these criteria and recommend the best fit for your business. It is free, takes about 2 minutes to get a quote, and there is no obligation. We are OFCOM regulated, rated 4.3/5 on Trustpilot from 1,000+ reviews, and we have been helping UK businesses with their communications since 2008.

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Still Have Questions?

If your question was not answered here, we are happy to help. Call us on 0203 006 1011 or get a free VoIP quote. We will answer your questions, compare providers, and give you an honest recommendation with no pressure and no obligation.

Compare The Networks. Making UK business phones simple since 2008.