BT have announced that their ISDN will be switched off by 2025, starting in 2020! But what does that mean? Is your company ready for the change?

ISDN stands for the Integrated Services Digital Network and comes in two flavours: ISDN2 and ISDN30 which each allow for 2 and 30 channels per line respectively.

The switch-off means that business using these services will no longer be able to be used.The plan is to move them onto a technology that for some is brand new and for others is as old as you can remember.

What do BT have planned for the 3 million channels that are still running through the ISDN?

Are there any actual benefits to using SIP over the ISDN?

In a word: YES. 

So what is SIP?

SIP stands for Session Initiation Protocol. VoIP is a part of SIP. SIP is used to establish modify and terminate multimedia sessions such as VoIP calls.


In an ISDN setup, only the phones that are in your building are able to access your business's number, meaning that if an employee can't make it to the office, they will not be able to contact their customers from home. instead they will have to use their mobile or personal landline.

In a VoIP setup, you can give your employees a phone to keep at home for such an occasion and have it log in to your phone system as if it was any other phone on the network.


By implementing SIP this allows the employee to keep their extension number and it won't cost them or you an extra penny. Another alternative is using a softphone - an app that can be downloaded onto mobiles or computers and used again as if it were an extension on your phone system.


Freedom of location: 

As long as you can access the internet, you can access VoIP. Furthermore you can get a number that presents itself to be in any location. Also available are the designated non-geographic 03 numbers!

You can also have multiple branches all over the UK and even the World, and your Japanese team can talk with your Italian team using extensions as if they're just in the next office.


Disaster recovery:

If your ISDN lines go down, your phones are down, and there's no telling how long it could take for your system to be back up and running. If you have no lines, you have no phones and that is that.


With VoIP your lines are virtual, and can be carried over any internet connection, be it ADSL, leased line, wireless P2P or 4G. This means you can instantly fail-over to any other means of connection should your main internet access go down, leaving your phone lines unaffected.

Lower costs:

An important consideration for any business is call costs, and a VoIP service can not only slash your line rental costs, but save you money on things like calls to mobiles and international calls.


You can also make internal calls for free no matter where someone physically is, as long as they have a connection to the internet in their office or on their soft-phone. This is useful if you have a fleet of mobile workers.


With ISDN30 if you want to be able to have more than 30 channels, you're a call centre for example and have just taken on your 31st employee, then you'll have to ask your supplier for a new line to be installed. This process will take many weeks and months for it to take place due to several factors such as having to dig up roads and pavements in the process. Baring in mind the rental on a new line does not come cheap! 


With VoIP you have as many channels as your bandwidth can handle - you can get calculators online for this sort of thing, but the important number if doing a speed test is your upload speed.


Looking the other way if you have an ISDN30 line but only 20 employees then you're paying for 10 channels you will never use, with a VoIP system you pay for what you use, from a single self-employed trader to a multinational corporation with over 10,000 employees.

So why wait?

With all these advantages of VoIP over ISDN, you may be wondering why you should wait until 2025 to move your systems over. The simple answer to that is: you shouldn't.

By the end of 2018 42% of firms will send 100% of their traffic using SIP



SIP Trunking for your business

Benefits and drawbacks to SIP trunking:

Moving office?

Number flexibility with SIP trunking offers a way to maintain your current number easily, even when moving out of the area. Saving you the cost of changing company print, websites, stationery and telling your customers whilst maintaining the perception that you still have a presence in the area you’ve moved from.

Need to improve your data connection?

As a company ask yourself one question;


What would happen if you can't connect to the internet?

Businesses rely on connectivity make sure yours is up to the job.

Protect Yourself from Toll Fraud


Hacking and abuse of business telephony is becoming as big as credit card fraud. With this type of abuse, the cost of the calls falls to your business.