Award-winning SIP Trunks

Connect your PBX to the PSTN in minutes.
Trusted by over 8,000 businesses
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Why Gradwell?

Our own network

We operate and optimise our own network, security and systems directly from our HQ.

Trusted by thousands

Thousands of UK SMEs rely on us for secure and cost-effective SIP trunks every single day.

Resilient and secure

We are ISO 27001 certified and our Network Operations Center monitors our systems at all times.

Recommended by the best

Our SIP Trunks are preferred by 3CX, with a native 3CX integration and setup.

3CX solutions provider

What are SIP Trunks?

Designed to replace traditional phone lines, SIP Trunks use broadband internet connections to connect your business phone system (PBX) to the traditional phone network (PSTN).

sip trunks diagram


We offer some of the most competitive rates available.

SIP Trunk only
One channel included

Per month, per channel

SIP Trunk + Minutes
One channel included

Per month, per channel

Not sure how many channels you need? Chat to us!

All prices quoted are minimum possible. All installations require a £25 setup fee. View our full tariffs here. International minutes available at extra cost.

SIP Direct Routing Network

Trusted SIP suppliers

We take pride in the resilience of our network. That’s why we’re trusted by hundreds of organisations for crucial SIP services.

We’re also one of only a handful of suppliers to have 3CX preferred status.

Specialist SIP services

We offer a range of bespoke SIP products

Direct Routing

Turn Microsoft Teams into your business phone system.

High Volume

A dedicated platform for high call volumes.

Specialist 3CX SIP

We’re a 3CX-preferred SIP Trunk provider.

Industry recognition and accreditations
Comms National Awards
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Comms Council UK
Fast 50
Sparkies Awards
BSI 27001
Best Companies

Trusted by our customers

We pride ourselves on finding solutions that help our customers, whatever their expertise.

We work with in-house IT functions with exacting requirements, to business owners and office managers who are new to telephony and communications.

Join thousands of businesses

We’ve helped organisations from across the UK take advantage of cloud-based communications tools. Can we help you?


High-volume SIP Trunks run on a separate dedicated platform built for high volumes of traffic and CAPS. This allows you to use the volumes you want without any issues.

 Not at all! You can have as many as you like from as many locations as you want.

Porting numbers can take up to two weeks depending on how many you have! We will request it as soon as possible and inform you when your number has been ported.

Built in the UK, we have a team of over 20 developers who are constantly evolving and advancing our technologies. With a range of packages to suit your business needs, you can tailor our products and services to suit your business needs and demands.

Simply give our team a call on 01225 800800 and they can set up extra users in a matter of minutes.

Gradwell has a wide range of connectivity options available that are suitable for running our SIP trunking services over. In just a few questions, our team will be able to advise which connectivity option is suitable for your business.