The PSTN and ISDN switch off

What is the PSTN switch off?

The Public Switched Telephone Network has been the basis of the UK’s telephony infrastructure since the first phone lines were introduced back in 1875. The PSTN supports several products from BT Openreach that are sold to businesses:

  • PSTN enabled landlines, like PBX phone systems
  • Integrated Services Digital Network (ISDN) lines — these could be ISDN2 or ISDN30 lines
  • Asymmetric Digital Subscriber Line (ADSL) broadband connections


BT Openreach has decided to retire the PSTN, and the system will be entirely switched off on December 31, 2025. If your business communication relies on any of these technologies, you’ll need to adopt a new system before then.

Why is the PSTN being switched off?

The PSTN consists of hardwired copper lines that connect individual phone lines to the telephone exchange. The same copper connections have been in place since the PSTN’s introduction back in 1875.

The equipment that makes up the network is reaching its end of life. Maintaining the network is becoming increasingly challenging, and the cost implications are outweighing the benefits of keeping the system functioning.

Therefore, BT Openreach has decided to gradually retire the PSTN and services that it supports. Instead, all homes and businesses will need to switch to new, digital alternatives for their voice services and internet connections.

BT Openreach is gradually expanding a ‘stop sell’ across the UK, hoping to cease all sales of PSTN services by September 2023. After this date, it won’t be possible to purchase a PSTN or ISDN phone line, or even make changes to an existing connection. 


What does this mean for business?

    The PSTN switch off means that businesses using a traditional landline or office phone system will need to find a new digital phone line. If your cur-rent business broadband connection operates using the ASDL network, you’ll also need to switch your broadband over too. 

    Digital phone lines

    For businesses that need to switch their phone system, hosted VoIP is the premium solution. It has all the features of a PSTN or ISDN phone system but connects calls over the internet.

    VoIP offers almost instant connectivity and boasts additional features that can help businesses prepare for the future of work. You can learn more about the benefits of VoIP here.

    Full fibre broadband

    Ultrafast full fibre broadband is the ultimate replacement of ADSL broadband, but it’s not available everywhere. To support the transition, BT Openreach has introduced some interim solutions:

    • Fibre to the cabinet (FTTC)
    • Single Order Ethernet Generic Access (SOGEA)


    Discover our business broadband options here.

    Learn more…

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