Award-winning SIP Trunks
Connect your PBX to the PSTN in minutes with Gradwell’s trusted SIP Trunks.

What are SIP Trunks and how do they work?
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) without needing to replace your existing hardware.
With the PSTN network due to be switched off by 2025, now is an ideal time to experience the benefits of connecting your business phone system to the internet.

Benefits of SIP Trunks
Cost effective
Lower installation fees and monthly costs, including DID provisioning and call charges for both national and international numbers.
Improved service levels
Ensure that customers can reach you, wherever they (and you) are at a lower cost and via a quality connection.
Flexibility
Change location, expand into new markets and forward calls at a moment’s notice without any business disruption.
Easy management
Instantly provision additional resource as needed, on a permanent or temporary basis.
Flexible numbering
Regardless of physical location – even if this changes – present local, non-geographical or international numbers as needed.
Easy to scale
SIP Trunks are a cost-effective way to easily scale up or down depending on your business requirements.
Why Gradwell?
We are the UK’s SIP pioneers and we take pride in the resilience of our network. We have a team of over 20 developers who are constantly evolving and advancing our technologies. That’s why we’re trusted by hundreds of organisations for business-critical SIP services. See what else makes Gradwell stand out from the crowd…
Our own network
We operate and optimise our own network, security and systems directly from our HQ.
Cloud based
All of our SIP Trunks operate in the cloud.
Resilient and secure
We are ISO 27001 certified and our Network Operations Centre monitors our systems at all times.
Trusted by thousands
Thousands of UK businesses rely on us for secure and cost effective SIP Trunks every single day.
Recommended by the best
We are one of only a handful of suppliers to have 3CX preferred status, with a native 3CX integration and set-up.
Easy management
Manage your SIP channels through our easy-to-use centralised portal.
Specialist SIP services
- Direct Routing
- Specialist 3CX SIP
- High Volume
Use Microsoft Teams as your business phone system. Direct Routing is the process of connecting Microsoft Teams to the traditional phone network, or PSTN. It is an increasingly popular way to turn Teams from a powerful internal communications tool to a full-scale unified communications platform.
We are a market-leading 3CX solutions provider – from onboarding and setup to support and maintenance, we help businesses feel secure when purchasing the 3CX system. Our end-to-end packages all include UK-based support, SIP trunks, connectivity and hardware. Deployed in a highly resilient cloud to guarantee service levels – not included in most suppliers’ standard offering.
We have designed our own high-volume SIP Trunks specifically for customers needing high call-per-second and high channel capacity. Integrating directly with your existing PBX, our high-volume SIP Trunks allows you to take advantage of the cloud-based solutions, without replacing your existing equipment.

Join thousands of businesses
