SIP Trunks – phone lines for the modern business 

Make no mistake, SIP trunks, no matter what anyone says, are the future of telecommunications. And the current in fact. 

In fact, BT Openreach have just announed (summer 2015) that ISDN will be ended in 2025. 

SIP makes Geography Irrelevant! SIP makes flexibility Instant! 


We have 25 years experience in business and telecommunications so we have seen alot of things come and go. Analogue was replaced by digital. Now SIP is replacing digital  – ISDN in other words. 

90% of the phone systems we are installing have either SIP or are a hosted system (cloud-based using SIP) – the days of people ordering ISDN are coming to an end. 

SIP Problems 

SIP has had a lot of bad press – but that is simply due to the connectivity being used and the resellers either mis-selling it or not having enough understanding on how to get it working properly and reliably. 

Connectivity has got a lot better and cheaper since 2013 with the UK Governemt even subsidising private fibre ethernet connections. Also, with the roll-out of fibre broadband and the resulting FTTC Ethernet (or GEO or Generic Ethernet Access) becoming available for businesses, SIP is now mainstream with cloud-based hosted systems. 

What is SIP? 

What is SIP? SIP stands for Session Initiation Protocol. More telecoms jargon! 

There are 2 sides to SIP. SIP trunks and SIP extensions. Please see the dedicated pages on this site for a full explanation of SIP trunks and SIP extensions as it is important to have an understanding. 

Basically SIP trunks are phone lines delivered on an internet connection. Normally, such an internet connection for small businesses will be a broadband connection (ADSL broadband or preferably Fibre ADSL broadband). As BT Openreach has been improving connectivity and infrastructure over the last few years, SIP now has a real place within the mainstream. This is particularly true with the costs of high-speed connections coming down and ‘proper’ same-speed-up-and-down internet connections with Service Level Agreements (SLA’S) becoming much more affordable (like FTTC – Fibre to the Cabinet, EFM – Ethernet First Mile and converged connections allowing the same connection to be used for both Voice and Data). 

There are many advantages of SIP trunks – please see the dedicated pages on this site - advantages of SIP. SIP extensions are IP devices or applications that use SIP to communicate on a Local Area Network (such as a non-propritary Polycom phone or conference phone or a soft phone application on a smart phone, laptop or PC. 

The main thing to grasp is that SIP is an international standard in telecommunications. A common language, if you will. All the telephone system manufacturers are making sure their telephone system platforms support SIP so you can be sure it is important. 

Basics required for SIP to work reliably 

For SIP trunks to work, there are a few critical things that must be considered as follows: 

  1. The connectivity must be correct – in other words the internet connection. There must be enough bandwidth. Furthermore, that bandwidth should ideally be delivered by the SIP trunk provider. 
  1. The telephone system manufacturer must have tested their system with the SIP trunks from the SIP trunk provider. If this is not in place, good luck! We doubt it will work. 
  1. The reseller/maintainer must know what they are doing – believe us….many DO NOT! 
  1. If bandwidth is limited, connections must be used JUST FOR SIP (is not also for data) unless a proper ‘converged’ product is used such as Gamma’s IP Assured Converged product which reserves bandwidth for SIP and prioritises the SIP traffic 

The main reason for businesses being unhappy with SIP is that one of these critical requirements has been ignored by the supplier, sales person or whoever. 

Is SIP cheaper than ISDN? 

The most frequent problem we find is that SIP trunks do not work as they have been bought because it is cheaper than ISDN. 

Whilst this may be the case, there are alot of sales people trying to sell SIP trunks as they appear cheaper – whilst it is now cheaper, this is only a recent occurence which is due to the better internet connection speeds being available throughout the UK. 

Do not be fooled by sales people who tell you that you can just use your current internet connection for SIP and cancel your ISDN – this simply is not true for the vast majority of small businesses. Even for bigger business, there is likely to be some re-configuration of the main interent connection required. 

SIP offers a lot of advantages of ISDN including some excellent Business Continuity features – please see the other pages of this web site for details. 

We can help with your SIP 

We can micro manage all SIP orders including supplying and maintaining your telephone systemand helping you discover what internet conenctions you can get at your premises and then project-managing the delivery of them for you.