£5.75 Per Basic Channel, £6.75 per Premium channel with 5000 local and national 2000 UK headline mobile minutes FREE CALLS INCLUDED per channel!

What are SIP trunks UK?

An SIP trunks UK is the virtual version of an analogue phone line. SIP stands for Session Initiation Protocol and it works with VoIP phone systems. SIP Trunking replaces traditional phone lines to provide cost-effective, fluid communication. A SIP Trunk is installed virtually over your businesses existing IP internet connection, unlike a traditional isdn with an extra cost for a single voice and data solution.

What are the benefits of SIP Trunks and their providers

Sequential Networks, enable you to lever the benefits of using SIP trunking. You can either combine your SIP trunks with VoIP for a full-fledged solution. Or, SIP trunks can work with traditional phone systems.

The benefits:

  • With SIP Trunks in the UK you only pay for the number of channels (lines) you need. Your lines are instantly scalable.
  • Combined with VoIP, reliability is increased through the ability to switch lines
  • SIP Trunks work with most modern phones
  • There is no hardware management or maintenance
  • Instant disaster recovery and business continuity
  • Free Internal Calls


SIP Trunks UK

SIP trunking fits with your unified communications strategy.  It’s easy to install and secure. SIP Trunks will integrate with your existing infrastructure.

Sequential Networks provide reliable, stable business sip. We operate advanced monitoring and diagnostics. Any network issues are quick remedied. Our SIP Trunks are conformance tested.

SIP compatible equipment is quickly configured to connect your SIP Trunks. Installation and implementation is quick and simple with Sequential Networks.

Our SIP product is more than just a line, it has a full feature set like a hosted VOIP system.

We know that customers face a challenge with the retirement of ISDN set for 2025 and some might not be ready to completely transition to hosted PBX and replace their on-premises equipment. We can now provide SIP with your existing PBX and when you are ready to make the change, simply move to hosted users and we even support mixed SIP and hosted

seat environments at the click of a button.

  • One solution to manage Hosted and SIP assets providing free on-net calls between Hosted seats and SIP channels
  • Enhanced SIP features like no other provider: call barring, DDI call forwarding, mobile and desktop applications to use SIP when out of the office
  • Advanced business SIP resiliency options
  • Scalable options to reduce, add and change, both channels and users when required in an instant
  • Simple and easy conversion from SIP to Hosted, ideal for upgrading
  • Secure and reliable platforms supported by BT, offering 99.9% uptime

All available

  • Auto attendant
  • Unreachable call forwarding
  • Enterprise trunking
  • Call logging
  • Call recording
  • UC for SIP DDI users


SIP Info
Set up fee FREE
Active channels £5.75 Per Basic Channel, £6.75 per Premium channel
In-active channels FREE on a Premium Channel
Contract term 12 months, no termination fees, ability to flex up during this term and add extra Channels and Users
Interop list 73 switches
SIP to ISDN Available
Call bundle 5000 local and national with no more than 15% to be to 03 numbers, 2000 UK headline mobile minutes per channel
End user portal access / management Yes
IM&P/soft client Yes – with Fixed and Mobile SIP Users
Skype plug-in Yes – with Fixed and Mobile SIP Users
Auto-attendant Yes
Compliant call recording Yes – chargeable

Your words

Why SIP Trunks?

Sequential Networks, a UK SIP Trunks provider, connects businesses with a nationwide network. We provide access to the public phone network with a more flexible and lower-cost alternative to ISDN voice calls.

SIP trunking service is less costly per channel than ISDN and more flexible in how and where geographic telephone numbers can be used. Installation and provisioning is far quicker. Sequential Networks deliver extremely robust business continuity.

SIP trunks UK


The Decline of ISDN

The market is transitioning from ISDN to SIP at an accelerated pace. Since 2008 around one million ISDN channels have ‘disappeared’.  SIP provision is the major benefactor. According to Illume*, research conducted during the last six months of 2013 found that almost 200,000 SIP trunks were added. This takes UK SIP trunks past the one million trunk mark for the first time.

ISDN channel decline is around 300,000 year-on-year** and if the current trend continues, the number of ISDN channels will fall below one million before the end of the decade.


Savings – 50% with line rentals and 25% on calls

Flexibility – Up to you! Add or remove Lines when you want

Control – Instant ability to change how and where you want calls to be delivered

Future – Voice & Data Convergence READY

Contingency – Ability to re-route calls to backup sites instantly

Sequential SIP Trunks offer a range of added value features with our SIP Trunks solutions including

  • Skype for Business
  • Number flexibility
  • Fraud management
  • Free internal calls
  • Free call termination to UK fixed destinations
  • Disaster recovery / business continuity-ready

Skype for Business with SIP Trunk

Improve collaboration, boost productivity and reduce cost with Skype for Business and Sequential SIP Trunks.

Connections have never been more important. Whether it’s connecting with customers or employees, access to a reliable, quick and clear connection anywhere, anytime is vital.

Skype for Business is an easy-to-use, feature-rich communications tool. It gives organisations access to voice, IM, audio, video and web conferencing, all via a single solution. Through a clever yet simple integration, SIP Trunk can extend unified communications beyond the office environment by connecting Skype for Business to the public network.

Our SIP trunk solution partner is qualified by Microsoft to interoperate with Skype for Business. This provides a seamless experience, making it an ideal solution for any organisation that is looking at implementing Skype for Business or that already uses it.

Combining the functionality of Skype for Business with the cost-savings and business-grade resilience SIP Trunk solutions offers, gives many benefits