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Top 10 SIP Trunking Providers in the UK

SIP TrunkingFinding the right SIP Trunking Provider, is just as important as choosing your phone system, as they work hand-in-hand to create your communication solution.

Let me guess, you have tried countless times to find an accurate guide to the best SIP providers, but the results haven’t been convincing.

You want to know what features make them the best providers, how they improve your calling experiences and be able to compare their qualities.

Today’s your lucky day because you have just found the all-inclusive guide to SIP providers.

By the time you have finished reading, you will have an exact idea of which SIP provider is right for your business.

So if you’re ready, let’s begin.

In this guide you will find

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Top 10 SIP Trunk Providers


Seeing as you probably don’t want to waste time scrolling through unrelated content, let’s get straight to the point.

Below are the top 10 SIP providers in the UK, ranked in no particular order.

How do you know that these are the best SIP providers?

It’s simple.

By SIP services offered, customer experiences, and small business-friendly features, you can be confident knowing that the following 10 SIP providers will live up to your expectations for business communication.




  • Affordable, flexible SIP provider
  • Free internal calls between numbers registered to your business
  • Save up to 50% on line rentals, and 25% on calls
  • Easily add/remove lines
  • Compatible with Skype for Business
  • Business continuity services

Rating: Sip

Founded in 2001, Gamma has established themselves as a leading provider for voice, data, and mobile services for businesses in the UK.

They offer cost-saving communication solutions for companies of all sizes that promise to cut down on your current phone bills.

The Gamma SIP service seamlessly integrates with the majority of IP-PBX systems in the UK, which means that they are also likely to be compatible with your phone system.

As their SIP runs on their network, you can also expect smooth functioning and a reliable connection on your calls.

In case of emergencies or relocation, Gamma also offers business continuity services where you can carry on using their SIP by quickly setting up on another device.

Vonage Business



  • Global telecommunications provider
  • Reliable and powerful network
  • Lower overall costs
  • Ability to handle more traffic and call volume
  • Access additional Unified Communications features


Vonage is a worldwide telecommunications supplier that specialises in delivering the best cloud-based communication solutions for businesses.

They offer a large pool of resources and expertise that ensures you have access to a reliable communication network at all times.

In addition to their SIP service, you can also use their cloud-based voice, video, data, and other UC features that offer the potential to elevate your business communication seriously.

Vonage SIP service easily integrates with your phone system, and even updates your IP PBX onto their cloud network.

So if you’re looking to cut down on costs, while increasing your SIP functionality and capability, then Vonage is a solid option.




  • Lower rates for line rentals and calls
  • Keep existing phone numbers
  • Scalable and reliable end-to-end SIP service
  • Business continuity services
  • Smooth integration with significant phone systems such as Panasonic, Cisco, and Gigaset


Spitfire is a telecommunications and IP solutions provider with over ten years of experience.

They provide holistic SIP services, ensuring the best sound quality when used in conjunction with Spitfire Ethernet and Voice Approved Broadband.

Not only are you able to keep your existing business phone numbers, but Spitfire also provides telephone numbers from different regions in the UK and abroad, that are all routed to your SIP at your office location.

Scale your solution to fit your business communication needs by quickly adding and removing lines at will.

Spitfire business continuity services also include features such as call divert to your mobile and home numbers.

They ensure that you are always connected to your business communication network.

BT Business

BT Logo


  • From £13/month with unlimited UK calls
  • Simple pricing plans
  • Free calls between BT SIP Trunks
  • Straightforward setup and launch process
  • Compatible with major phone systems, including non-BT systems
  • Business continuity services


BT is a household name within UK telecommunications, providing business-friendly communication solutions alongside simple pricing plans.

Their SIP services are much cheaper than traditional ISDN lines, and also include free calls between other SIP Trunks from BT.

Seeing as they own their network, your calls are run on a reliable system that ensures you receive the highest quality service.

What’s more, you can expect an even faster and more reliable calling experience when you use BT SIP in conjunction with BTnet.

Even if you are using a non-BT phone system, it’s still relatively easy to connect to BT SIP through the BT SIP Trunk Gateway.

This flexibility is what makes BT consistently popular with UK businesses.




  • From £4/month with free set up
  • Ability to bundle multiple numbers
  • Lower calling costs
  • Used by over 22,000 businesses
  • Flexible service that allows you to scale and customise your communication quickly


Operating since 1998, Gradwell has become a leading SIP provider for UK businesses by offering a better, affordable alternative to traditional ISDN.

Forget about ISDN line rental charges, and save further costs by bundling your numbers for a simpler calling experience.

Gradwell award-winning services in SIP, VoIP, broadband, fibre, and other Cloud products have earned them a solid 4-star rating on Trustpilot.

Customers praise the helpful customer service, reliable communication, and the high quality of calls.

They boast an impressive client list with the likes of Cath Kidston, Zoopla, and Ted Baker, indicating that Gradwell is a safe option for a business SIP provider.




  • Cloud-based SIP provider
  • Supports remote working by providing numbers from worldwide locations
  • Simple pay-as-you-go basis and discounts for committed users
  • Scalable SIP service with no limit on available calling capacity
  • Reliable connection with the Twilio-owned network
  • Small business-friendly features to improve your communication


Twilio is a cloud communications provider that offers voice, video, and data communication solutions.

Based in San Francisco, they have built a global presence through their reliable SIP services and features that support businesses communication.

In addition to providing a flexible pay-as-you-go pricing plan, Twilio also offers a discount for users that commit to using a specific monthly volume.

This gives you more control over your costs, as you can choose a plan that is in line with your communication and budgetary needs.

Furthermore, Twilio has business-friendly features that increase the functionality of your business communications.

These features include call recording, toll fraud protection, and private connections.




  • No long-term commitment
  • Up to 84% cheaper than ISDN
  • Domestic calls starting at 5p/min and Cheaper international calling rates
  • Real-time online billing
  • 99.99% guaranteed uptime and 30-day money back for unsatisfactory products


With over ten years of experience, Xinix is a trustworthy business telecommunications provider with a variety of small business-friendly solutions.

They focus on delivering high-quality communication and SIP service while maintaining competitive prices.

Xinix owns their network that supports their SIP services and ensures that you always receive a stable connection for smooth communication.

You can also route different numbers from locations around the UK, directly to your office location.




  • Two different SIP plans for businesses that need either two inbound channels or 3+
  • Calling rates begin at just over 0.5p/min for major UK mobile operators
  • No setup and hidden monthly usage fees
  • Easy billing with online pre-pay system
  • No contracts
  • Fast, personable customer support


Based in the UK, DirectVoIP is an IP telephony provider that specialises in hosted VoIP PBX and SIP Trunks for businesses of all sizes.

They understand modern business needs and thus, prioritise delivering communication solutions that ensure you receive the best value for money.

Their industry experience and extensive coverage also allow them to efficiently regulate call traffic and support businesses that receive a large volume of calls.

The DirectVoIP pricing plans for their SIP also enable you to pay only for the calls and channels that you use, which provides both savings and control over your communication.




  • Cost-effective SIP provider
  • Rolling monthly contracts and free registration
  • Compatible with a large variety of IP-PBXs
  • Intuitive platform and customer-friendly design
  • Self-service 24/7 online portal
  • Additional business-friendly features such as call recording, conferencing, and voicemail


VoiceHost are a popular UK-based VoIP provider that provides solutions for SIP trunking, hosted PBX, VoIP telephony, and hybrid PBX systems.

They have a strong foundation in software development, which translates into high-quality SIP services and reliable business communication solutions.

Although they are software-based, VoiceHost ensures that their SIP remains user-friendly in that it is easy to use and configure without requiring advanced technical skills.

VoiceHost also operates their call routing infrastructure, which guarantees smooth function.




  • Low-cost, high-quality SIP services
  • Pay-as-you-go pricing plan
  • No monthly contracts
  • Scalable solution with easy addition and removal of numbers
  • Compatible with most IP-PBXs


Based in the United States, Net2Phone is a VoIP and cloud telephony provider that offers attractive SIP services for all types of businesses.

Since their inception in 1990, they have accumulated a wealth of experiences working with various industries, and thus offer solutions that aim to meet your unique communication needs.

Net2Phone also allows you to connect and route numbers from different locations to your office location to centralise and streamline your communication.

Their SIP service is compatible with a variety of phone systems, which saves you from having to buy further hardware.

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Breaking Down SIP



If you want to make the most out of your SIP service, then you need to have a clear understanding of what it covers.

SIP stands for Session Initiation Protocol and is defined as a ‘session’ in which you connect your phone system to the VoIP network to make calls and other forms of communication.

SIP replaces traditional and expensive ISDN lines that require expensive line rental charges, as well as additional hardware.

With SIP you continue to make and receive calls, as usual, connecting to the public switched telephone network (PSTN), all while saving on unnecessary costs.

Moreover, SIP enables you to use a greater variety of devices in your phone system such as computers and mobile devices.

As long as you have an Internet connection and IP network, then you are good to go.

A SIP Trunk holds your SIP lines, the number of which depends on your business communication needs.

From here, you obtain a SIP address/account from a SIP provider, install a SIP client on your communication device, and use a stable Internet connection to facilitate your communication.


Benefits of SIP


As a business owner, you most likely have a good idea of SIP and its advantages. But perhaps there are some benefits of SIP that you have missed, which could help you better understand the importance of choosing the right SIP provider.

To make your life easier, here’s a complete summary of the benefits of SIP:

  • Save on costs with simple, affordable pricing plans that allow you to pay for what you use as SIP trunking is typically sold on a per-channel basis according to what you need
  • Cheaper than traditional ISDN
  • Facilitates flexible communication through delivering voice, video, and data through a range of electronic devices
  • Easily scalable to your business due to SIP being software-based, which allows for easy configurement and updates
  • A smaller investment in telephony hardware
  • Straightforward and fast troubleshooting, since transmission happens completely online
  • A higher level of capability as SIP can support many users with customised settings and features


How to Choose the Right SIP Provider


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Hold on a moment!

Just before you leave, I recommend that you read this last part about choosing the right SIP provider.

This is the final leg of your journey to the ideal SIP provider for your business, and once you are through, you will be able to call yourself an expert on SIP providers.

Without further ado, let’s go through what you need to know to choose the right SIP provider for your business.


SIP providers need to provide a SIP service that easily grows with your business, with flexible features such as adding and removing lines at will.

They should be able to support your business communication, whether you require minimal or large-scale calling capabilities.


Your SIP provider should provide a platform for high-quality calls and communication, through a stable network and connection.

They also need to have fast and reliable customer support, so that your issues are quickly fixed, and your business does not end up losing potential and existing customers.


Voted as the top concern for businesses, you have to ensure that your SIP provider has put in the best security measures to prevent hacking, fraud, and data breaches.

Since you are trusting them with your communication, they need to prove that they can protect you from harmful activity.


Before you make any purchasing decisions, make sure that the SIP provider is compatible with your current phone system.

This saves you from the unwelcome surprise of having to purchase new hardware and wasting precious capital.

Additional Features

What additional features does the SIP provider offer that helps with your business communication?

Make a list of what features you expect from your SIP provider such as 411, voicemail-to-email, conferencing, auto-attendant, and so forth.

Well done!

You have successfully made it to the end of this guide to the top SIP providers. And, are fully capable of beginning choosing the ideal SIP provider for your business.

Various SIP providers offer different payment plans and features, so make sure that you carefully inspect that your chosen provider meets all of your communication needs and will easily scale for future business growth.

Good luck, and let us know how it goes!


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