The 2025 ISDN and PSTN Switch Off and Its Effects On My Business.

The 2025 ISDN and PSTN Switch Off and Its Effects On My Business.

Whether you’re ready or not, it’s happening!

In 2017 BT announced Public Switch Telephone Network (PSTN) and the Integrated Services Digital Network (ISDN) would no longer exist.

“Why” I hear you say…

Many phone lines today are using copper cables and unfortunately, both the PSTN and ISDN are becoming increasingly pressurised to meet the demands of the ever evolving and fast paced business environment that we see today. 

With the switch off happening in December 2025, we are set to see fixed telephone networks replaced with digital systems such as IP telephony and Voice over internet protocol (VoIP).

So ultimately, whilst this is a good thing, I’ve listed a few details below to help you to understand it a little more.

Will My Phone Lines Stop Working?

Yes, all analogue, ISDN2, and ISDN30 platforms will be retired in 2025 so if your business is currently using one of these legacy platforms to deliver your telephone calls you need to make sure you have a plan in place for the switch off.  Ensure your business telecoms are unaffected by changes to the wider network with High Quality internet, SIP compatible telephone systems and a robust data network infrastructure. 

Does This Just Effect My Phone Lines?

No, any technology that you have operating through your current PSTN, or ISDN will no longer function. This may include alarm systems, lifts, and door entry systems to name a few.

What Should I Do?

Start planning now! If you’re not ready for the switch off when it happens, your business will suffer. Ultimately, leading to operational issues. 

Your plans should include the following.

  • Seek advice via an on-site infrastructure audit.
  • Understand if your current telephone system is suitable for your requirements moving forward. For example, are you gearing up for hybrid or remote working.
  • Some systems may be ready for the switch off, but it’s important to check if you need to upgrade to an internet-based solution to replace the current PSTN or ISDN.
  • You may need to upgrade to an IP based solution for compatibility. If you need to retain legacy equipment you may require analogue convertors.
  • Moving to IP enables you to embrace the latest collaboration tools. For example, you can integrate your telephone system with your Microsoft 365 environment, allowing you to make and receive calls from one application. 

Is IP Better Than PSTN and ISDN?

The quick answer is yes. IP telephony allows us to embrace the ever-evolving possibilities of cloud-based communication. You will have access to higher quality audio, resiliency, redundancy, and scalability.

What is Best for My Business After PSTN and ISDN?

There are many options. From a physical phone box with SIP trunking to a hosted cloud-based telephone system with IP handsets. We would work with you to understand your requirements.

You may need to upgrade your internet connection to ensure that it has the capacity to withstand all your business tech requirements.

How much will this cost?

This is dependent on your requirements and current infrastructure. However, switching to a cloud-based system can save on expenditure in the long run. 


Being prepared now will prevent any big panic, as December 2025 really is just around the corner. With so many options available, talk to our experts to find the best solution for you. 

To get yourself and employees ready for the switch off, get in touch with us today on 01642661888 or email us at

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