Ready for the BT ISDN Switch Off?


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BT have recently announced their plans to switch off the ISDN network. With over 2 million businesses still running their telephone systems on ISDN telephone lines these businesses are now wondering what their options are? This is where we can help your business to make an educated choice instead of a panicked one.

What can your business do to prepare for the ISDN Switch Off?

We suggest you seek some expert advice on the options available before you agree to anything. Some of the major Telecoms Providers are using pressure tactics on customers who do not understand what these changes mean for their business. Don’t be tempted to automatically renew your existing contracts for the sake of an easy life - getting tied into lengthy contracts on the wrong technology is a bad idea!  

At Switch Networks we take the time to understand how your business works so we can offer a solution that will fit with your business and your budget. Our qualified Engineers can point out any potential issues as well as the advantages. We offer a wide range of solutions and we are happy to run through what each service can offer your individual business. 

What is an ISDN line?

ISDN simply stands for Integrated Service Digital Network.

An ISDN line works on a copper network which was originally installed in 1986. ISDN lines were created to carry both voice and data simultaneously so were ideal for a business that needed to run concurrent calls and send data at the same time. Due to improved internet speeds in recent years, the preferred way to send data has been across dedicated internet connections such as ADSL and FTTC broadband.  

Why are ISDN lines being phased out? 

Over the last 20 years technology has evolved at a very fast pace. BT are phasing out the ISDN network  in favour of internet-based lines which offer the end user greater reliability and gives the overall network far more flexibility than the existing copper network. 

How Do I Know If I Am Using ISDN?

If you have a phone system that was installed more than 3 years ago and you have the ability to take more than one call at a time, it’s likely that you will be using an ISDN line to communicate with the rest of the world. 

Depending on your provider, there should be a reference to ISDN on your bill. Unfortunately, many telecoms companies make customer bills difficult to understand or they hide the information in different text. If it is unclear if you are using an ISDN or PSTN line then give us a call and we will be able to tell you quickly whether you are using an ISDN line or not. 

Am I Going To Be Cut Off Soon?

No. Although BT are no longer taking orders for ISDN from 2020, the proposed deadline for a final switch-off is 2025. If you are looking to replace your business telephone system before then, we strongly advise you to look at all the options available so that you are not paying twice in the long run. 

What is Replacing ISDN?

In simple terms ISDN is migrating from digital to internet based services called SIP and VoIP. Calls will be carried over your broadband (internet) connection. If you are already using a reasonably up to date phone system you may just need a clever piece of equipment installing so that your existing phone system can continue to work on the new SIP lines.

SIP Trunks

SIP Trunks are one of several solutions that will replace the soon to be outdated ISDN lines. SIP Trunks can continue to work with traditional on-site PBX systems using additional equipment.

The newer SIP trunk technology offers much more flexibility than ISDN lines such as the ability to  increase or decrease the amount of lines during busy periods without any long term commitment. Call manager software offers call centre functions at cloud level as well as other features including call forwarding and disaster recovery routing.

Another alternative would be a “VoIP” or ‘hosted’ system, A “hosted” system is not a physical system, it is in a server room somewhere in “The Cloud”. Effectively, your “phone system” is off-site and is programmed remotely.

Cloud Based Telephone Systems

A Cloud-based telephone system has PBX capabilities but does not require a physical system on site.  These systems are controlled through easy to use online portals that allow instant changes, offering business flexibility as well as scalability. A Cloud-based system can be used with desk phones, cordless handsets, a PC interface or an app on your mobile device. These systems offer lots of clever features such as remote working, call forwarding and disaster recovery routing. Powerful reporting insights are available through an online portal. 

If you choose a VoIP system, it is important that you don’t just choose the cheapest option. An experienced network provider is key as they will ultimately be in control of your system. 

Our Internet Isn’t Very good - Can We Use VoIP?

No is the short answer. A VoIP service relies on the strength of the internet connection it sits on. A weak internet connection will result in packet loss and conversations may sound robotic or the call drop completely. This is not ideal for a business, so a reliable internet connection is certainly crucial if this is the route that you are wanting to take. 

Fibre to the cabinet “FTTC” would be suitable for most small businesses, however, fibre to the premises “FTTP” or a “Leased Line” would be the most reliable connection to guarantee call quality and reliability. 

This is something we can help you with through our broadband services. Increasing the speed and reliability of your internet is certainly a wise decision to take to ensure the efficiency and stability of your business.  


Traditional ISDN (Integrated Services Digital Network)

ISDN is due to be switched off by 2025 across the BT network

ISDN circuits often require expensive hardware for additional lines such as line cards

Only fixed geographical numbers are available on ISDN circuits limited to exchange area

ISDN circuits often have an expensive mirror system set up as a disaster recovery system

Features can be complicated to use, expensive hardware/software is required to enable features such as call reporting and call recording

New Technology SIP (Session Initiation Protocol)

SIP trunks will replace the soon to be outdated ISDN lines with orders being stoppped in 2020 with BT

SIP trunks can be added to a system within 48 hours without the need for the additional hardware

Number flexiblility - SIP offers virtual numbers so that you can choose to present any number available

SIP offers flexibility, business continuity and disaster recovery solution as part of the service meaning additional back-up systems are not required

SIP has easy to use call reporting and recording features

If you are unsure what solution might be the best option for your business you have some time to decide before the ISDN Switch off so don’t worry. If you would like some friendly advice please give us a call on 01653 917000 or fill out the form below and we will take the time to get to know your business and help you to choose the best solution to suit your business needs.

ISDN advice form

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Switch Networks Ltd
Unit 1A, Park Farm Courtyard, Easthorpe Business Centre, North Yorkshire, YO17 6QX.