SIP Trunking

Bring your existing onsite PBX into the 21st century with the power of Connexin SIP Trunking.

SIP Trunking

Connexin SIP trunking offers a more flexible, lower-cost alternative to traditional ISDN for inbound and outbound calls. As a replacement for ISDN, SIP trunking connects your PBX to our network via the cloud to give you cheaper call rates and flexibility in how your telephone numbers can be used.

Brands that rely on Connexin SIP Trunking

Our Packages

We offer volume-based discounts as well as support for charities. Come and speak to us.

SIP Trunking

2000 UK landline mins
2000 UK mobile mins


per trunk per month

1 channel included

Setup fees apply

12 months contract


Important Info

Free calling minutes are to UK 01, 02, 03 landline numbers and UK mobile numbers only. All other calls are charged at the standard advertised rates. A minimum contract term of 12-months applies unless otherwise stated. All prices shown exclude VAT. For more information, please see our full terms and conditions.

Benefits and features of our SIP Trunking

Save money

SIP delivers less costly, more reliable connectivity than ISDN over an IP connection. It can save up to 50% on line rentals and 25% or more on call costs.

Free internal calls

Perfect for medium or large organisations with multiple sites, not only will you save on your line rental and call costs, but you will also get free internal calls within your organisation and a whole host of great features.

Scale whenever

SIP trunking is ideal if you are moving, upsizing or downsizing and want to keep your existing numbers. Scale up lines during busy periods and back down again afterwards. You can add lines, take them away, split calls at any time. You are always in control.

Business continuity

SIP trunking can handle emergencies easily. They are inherently disaster recovery/business continuity ready, letting you reroute calls to an alternative location quickly and easily.

Number flexibility

SIP Trunkinng support business relocations by enabling a geographic number to be retained without call forwarding costs. We can also supply out-of-area geographic number ranges to make your organisation appear local, even without a physical presence.

Fraud protection

Hacking and abuse of business telephony are becoming as big as credit card fraud. Our SIP Trunking comes standard with fraud protection by monitoring unusual call usage.

Numbering & Porting

Bring your existing numbers to us or just get some brand new numbers from us.

Number Porting

With Connexin, you can port your existing telephone numbers into our platform to be used with your new SIP Trunks. We have porting agreements with all major telecoms providers in the UK so most standard number porting won’t be an issue. Your numbers will stay with you and if you decide to move on from us (hopefully not), you can port out the numbers to your new providers. We can port:

  • geographical numbers
  • non-geographical numbers
  • single numbers or multi-line numbers

Charges apply for both port in and port out numbers.


If you have just setup a new business and are looking for new numbers, or you are an established business that wants some new numbers, we can take care of that for you straight away. We have thousands of numbers, from different area codes, countries and non-geographic specific to choose from and we can get your numbers setup within a few clicks. If you are looking to stand out from the crowd, you can also choose from a wide selection of memorable numbers.

  • UK geographical numbers
  • UK non-geographical numbers
  • International numbers
  • Gold and Platinum numbers

Charges apply for new numbers.

Personalise your SIP Trunks

Get even more out of your SIP Trunks

SIP Trunk
Call Manager

SIP Trunk Call Manager provides you with all the benefits of our SIP Trunks together with a centralised inbound call management service with a host of features, accessed through an easy-to-use web portal and mobile app. Manage how inbound calls are routed within your offices via app or web portal, giving you total control.

SIP Trunk

Add as many additional channels as you need to your existing SIP Trunk. The more channels you have on your SIP Trunk, the more simultaneous calls you make and receive. Each additional channel comes with an additional 2000 calling minutes to UK 01, 02, 03 landline numbers, and 2000 minutes to UK mobiles.

UK Direct
Dial Numbers

Additional UK DDI numbers can be added to your SIP Trunk. With our SIP Trunking product, you can add as many numbers as you like.

Added Security for your SIP Trunks


The Payment Card Industry Data Security Standard (PCI DSS) is the proprietary information security standard defined by the major card companies to help combat fraud and protect consumer card data. With Connexin, additional security measures can be applied to our SIP Trunks to ensure the compliance of PCI DSS.

Keep on top of your customers’ payment data with Connexin SIP Trunking.


Hacking and abuse of business telephony are becoming as big as credit card fraud. With this type of abuse, the cost of the calls falls to your business. But with our Call Guard service your business is protected from such activity.

  • Your calls protected from unusual usage.
  • Low cost for peace of mind knowing your calls are protected.
  • Avoid any unwanted expensive bills
  • Can be applied to all of your existing numbers.

Protect your business from costly phone hacking and misuse.

Need something a bit more bespoke?

We put together bespoke SIP Trunk systems for customers who need a solution designed around them and their needs. Whether that’s a call centre, an all-in-one communications platform, or even a system designed around remote working, we work with you to get the right solution for you and your team.

Some of the PBX vendors we work with:

Get A Quote

Get a no-obligation, bespoke quote from our team of specialists using the form below. We’ll walk you through your requirements and help you build a system that works for you.

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