The BIG switch off

Author - Arlen Pettitt

Date published:

Andy Watson of Unified Business Communications explains what businesses need to think about with BT having announced that they will be switching off the PSTN (Public Switched Telephone Network) and ISDN (Integrated Services Digital Network) networks by 2025 and will no longer accept any new orders or amendments to services applicable to any PSTN or ISDN products as of 2023.

While 2023 and 2025 seem a long time away they will soon creep up on us and the upcoming switch-off means that PSTN (Public Switched Telephone Network – analogue) and ISDN (Integrated Services Digital Network – Digital) lines are now considered a legacy product.

Once the switch-off has taken place, customers will be migrated to a single IP network using SIP (Session Initiation Protocol) which will ultimately replace all legacy network and platforms. If your business uses PSTN and ISDN lines as a service, the switch-off is going to have a significant effect on your organisation unless you can migrate your own system over to a VoIP (Voice over IP) service.


When the time comes your telephone service provider will assist you by migrating your existing telephone lines to an alternative Internet based technology, for example Hosted Voice or SIP Trunks.


A fast and reliable internet service is the key to enabling the new VoIP technologies. Look for a broadband provider that can offer fibre services such as FTTC, FTTP, SoGEA, Superfast Fibre connections or a Leased Service.

Voice over IP

Choose from a Hosted Voice system in the cloud, on-premises IP phone system with SIP Trunking, or a PSTN/SiP Gateway to SiP Enable your Legacy Equipment. All services transport your voice traffic over the internet (VoIP) technologies and provide flexible and cost-effective alternatives to traditional fixed line telephony.

VoIP Provides:

1. Remote working:

VoIP promotes remote working. Staff can log into your VoIP system from anywhere using an Internet connection.

2. Multi-functional:

VoIP isn’t just limited to voice calls, VoIP phones can be used for a whole host of other functions, including videoconferencing and mobile apps.

3. System Integration:

Because VoIP technology uses the Internet, it is possible to integrate it with your other business systems, such as email clients or customer records.

4. Scalability:

VoIP technology is highly scalable and can grow with your business. New phone lines can simply be added, reassigned, or removed according to your ongoing business needs.

What you need to consider before moving to VoIP

Before you migrate to a VoIP solution there are a couple of things that you will need to consider:

Is your internet connection good enough to deliver VoIP?

While VoIP doesn’t use very much data compared to other services such as video, you need to ensure that your bandwidth has the capability to deliver voice services on top of everything else your organisation uses the Internet for. Without good Broadband speeds the quality of your voice calls could diminish.

Does your office phone system support VoIP?

Most new office phone systems support VoIP, but if yours doesn’t, you will either need to replace your entire phone system with an IP-enabled on-premises PBX, replace your PBX with a Hosted VoIP Solution or purchase a SiP Gateway to VoIP enable your existing PBX.

When should you migrate to VoIP?

Businesses should consider migrating to VoIP/SiP = sooner rather than later. 

Depending on the Broadband capabilities in your area, this may not as yet be possible.  Contact your phone or internet service provider and ask them to check what broadband is available in your area and if it can support VoIP services.

Andy Watson

Unified Business Communications

Stoneygate House, Stoneygate Lane, Felling, Gateshead NE10 0HJ

t. 0191 201 2112

e: [email protected]


Photo by Pawel Czerwinski on Unsplash

Back to hub