ISDN Shutdown What to do now

ISDN has been widely used across UK homes and businesses for decades delivering digital broadcast-quality voice and data across the public telephone network. But its days are finally coming to an end.

ISDN is due to be switched off by 2025 in the UK. No more new orders will be placed as of 2020. Many businesses have already moved to new VoIP systems and they are noticing a number of key benefits. With the ISDN switch-off looming, we've put together a quick guide on what's happening and how you can prepare. 

What exactly is ISDN and why is it being switched off?


Integrated Service Digital Network (ISDN) is a phone system that allows voice and data to be transmitted via digital lines simultaneously. It launched back in 1986 with much celebration as businesses could now support their phone lines and video conference at the same time.

ISDN introduced faster speeds and a digital connection bringing about a plethora of benefits to businesses. This included increased productivity, clearer connections and a decreased number of interruptions and distortion.

But now, ISDN is a bit of an outdated system. Businesses can benefit more from a Voice over IP (VoIP) system that works via an active internet connection. Because there are no physical lines involved, it provides even faster connection speeds.

What are the real benefits?


VoIP or SIP (Session Initiation Protocol) are phone systems that allow for making calls over the internet. It is essentially a virtual telephone line, which allows for the cost associated with phone lines and hardware to be dramatically reduced.

Paying for line rental may be in the past. In addition to the cost savings, there are far more benefits for businesses when it comes to flexibility, scalability and future proofing.

A digital line provides many benefits when it comes to video conferencing, managing call directions, increasing or decreasing the number of connections and transferring calls between locations. 

What can you do to prepare?

Although the shutdown won’t officially happen until 2025, it’s still important to start thinking about how to prepare for the ISDN switch-off. (If you haven’t already.)

Luckily, switching from ISDN to a VoIP phone system isn’t as complicated as it seems. It's a relatively straightforward process. But you do have to make sure your business has good enough internet connection to deliver VoIP. Luckily, in this day and age, most businesses will. 

Is your business compatible with a VoIP system?

Ideally, you would need internet speeds above 2Mbps for a small business, but it depends on the type of business you are in. Larger business with more demand may need faster speeds at around 5Mbps.

You’ll also need to check that your current phone system within the business will support VoIP. If it doesn’t, you may need to replace your phone system. If you don't want the hassle of that you can invest in a new new PBX (the box that connects you to the external phone network) or try a hosted telephony system i.e. the Cloud.

  • Check your contract: If your current telephone contract is due for renewal or you're out of your contract period it is the perfect time to migrate to VoIP or SIP technology. If you’re still in contract, you can plan your exit date based on your T’s and C’s.
  • Profile your company: When migrating your telephony system, you’ll want to check how many users and handsets you will need. Then find a system that suits and is compatible with your exact needs.
  • Set your budget: moving to a new system can help you save money. It’s worth checking what your current budget is to compare. There are different solutions available so you can easily adjust to fit your needs.


Easily switch for a better connection

With Onecom and Mitel we can help you easily migrate to a new hosted telephony system to experience better business communication and collaboration. We may even be able to help you switch and get your new system deployed easily and quickly with minimal disruption to your business.

Mitel’s cloud business systems are powerful, flexible and scalable to suit your business requirements. With faster communications, it can help give you a competitive advantage and future-proof your business growth.

If you'd like to know more about upgrading to a VoIP system, get in touch today. We can help you make the switch. 



Onecom is the UK’s largest independent business telecommunications provider delivering fixed line, mobile, unified communications and connectivity solutions. It has partnered with the best technology and communications partners globally to offer customers the pick of the best solutions on the market. Knowing that no two businesses are the same, Onecom takes pride in understanding its customers and tailoring solutions to meet their specific needs.

get great content like this weekly
Ready to talk to sales? Contact us.