Flexible solution

Our SIP trunking solution offers your business a lower-cost and more flexible solution than ISDN for your outbound and inbound voice calls.

It provides a connection between your PBX and the PSTN using Ethernet, broadband or a private circuit connected to our national network.

Our SIP trunking solution costs less per channel than ISDN and provides more flexibility in how and where you can use geographic telephone numbers. It is also faster to provision and install, and it provides very strong business continuity.

Compatible with all major IP PBX brands

SIP trunking can support two channels for small businesses with a PBX to an unlimited number of channels for contact centres and larger companies.

Our SIP trunks are compatible with all major IP PBX brands utilised in the UK. If you have a PBX, then you can change to using our SIP trunking solution and immediately receive a phone service that is more resilient, more flexible and less expensive.

If you do not have a PBX, then consider using our hosted phone system.

Benefits to using SIP trunking

There are many benefits to using SIP trunking. You will spend less money on line rental and call costs, as SIP trunking provides connectivity that is more reliable and less costly than ISDN using an IP connection.

You can save up to 25% or more on the cost of calls and up to 50% on the cost of line rentals.

SIP trunking is ideal for medium and large businesses that have multiple sites since besides saving money on call costs and line rentals, you will also receive free internet calls within your company and many other outstanding features.

If you plan to upsize, downsize or move and wish to retain your current telephone numbers, then SIP trunking is the perfect solution. During busy times, you can scale up your lines to accommodate demand and then scale back during periods of reduced activity. In addition, you can always remove lines, add or remove lines, or split calls whenever the need arises.

Need help with your SIP Trunking?

Let us help you find what’s right for you.

What we do

We provide landline communications, business mobiles and connectivity solutions for businesses


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Fixed Lines

Save money on your line rental and call charges.

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Comprehensive connectivity and networking solutions.

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Phone Systems

A wide range of flexible business phone system packages.

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What our clients say

“We’ve dealt with Synergy for almost 8 years now. With Synergy we enjoy competitive pricing but just as importantly for our business, we get a fast and efficient service. Having Synergy manage our Vodafone account has taken so much of the hassle away from having to deal with call centre staff at Vodafone. We get straightforward, common sense advice with Synergy and they now manage all our communications not just the mobiles. Looking forward to 10 years and beyond, great service guys!”

Navin Kabariya, Jaysam Contractors

“We have dealt with Synergy for over seven years and have always found them to be polite, friendly and efficient. They have helped us negotiate and renew several landline and mobile contracts, always ensuring the best deal for us.”

Trevor Darton, First Choice Marshalls

"Having been with Synergy Mobile since June 2007, we were pleased to extend the good relationship that had been built and to switch providers on all landline services early this year. The transition was painless and we look forward to continuing with Synergy and our Account Manager for many years.”

Jan Lindsay, Michael Barclay Partnership

“I am always pleased and even surprised when I or my Company receives very good service however with Synergy I am very happy to say that I have come to expect it from you because you always exceed expectations!”

Hazel Sadler, Mobile Freezer Rentals

“We recently had an issue with one of our phones and we just wanted to let you know that we were extremely pleased with our Account Manager’s involvement in the matter. He was excellent at providing updates and ensuring the matter was resolved efficiently. Thank you.”

Chris Rock, Cybex International

“Well done on this transition, you've done a great job at getting us all consolidated for which we are very grateful.”

Joe Binnion, Big Innovation

“Cheers for sorting the guys’ phones out, first-class service as usual.”

Nic Deveraux, Albany Hill Associates

“Many thanks for your help, a cracking service as usual.”

Chris Bull, PCS Logistics

“Thank you so much for your help, you solved my problem brilliantly. I don’t know how I would have dealt with all of this without you, I really appreciate it.”

Louise Bellamy, Professional Social Care Solutions