How will the ISDN switch-off impact your business?

7th July 2022

In 2025, BT is due to switch off ISDN and PSTN services. But what are they and how will the switch-off impact your business?

Public Switched Telephone Network (PSTN)

The public switched telephone network (PSTN) is the term used to refer to circuit-switched phone networks which are operated by a range of suppliers, generally national, regional, or local telephone companies. These systems send voice data through copper wires owned by the phone providers via analogue signals.

Integrated Services Digital Network (ISDN)

ISDN is a group of communication standards which allow the simultaneous transmission of video, voice, data, and other network services via the circuits found in the public switched telephone network (PSTN). Simply put, your standard phone line is utilised to send both voice and data over the same line. ISDN was introduced in the UK by BT in 1986, but since then connectivity technology has advanced considerably and ISDN has started to be outmoded.

Why the switch-off?

BT announced in 2015 that they were planning to turn off ISDN and PSTN services, mainly due to these technologies being unable to handle the volume or quality of voice data needed by modern usage.

Broadband speeds now are much faster than ISDN, and with ISDN lines being tied to physical locations, they can’t support flexible connectivity solutions such as those needed by remote workers.

What comes after ISDN?

Recent investment in communications networks within the UK has made fibre broadband services widely available and affordable to small businesses. This means that IP-based alternatives (like VoIP and SIP) are the most viable alternatives for your business post-ISDN.

Voice over Internet Protocol (VoIP)

VoIP is already in use by many organisations. It’s a cloud-based phone system, which means all your incoming or outgoing calls are sent over the internet.

VoIP has a broad range of additional features over more traditional ISDN systems such as:

  • Call recording
  • Ability to receive voicemails over email
  • Call queuing
  • Phone services accessible via multiple devices (mobile, desktop, tablet etc.)

Session Initiation Protocol (SIP)

SIP is a phone line carried directly over your fibre broadband connection, eliminating the requirement for an ISDN phone line in its entirety.

At Challenger, we’ve been providing SIP lines for years. We’ve helped many organisations make the switch from ISDN to SIP services. If this is something you’d be interested in discussing with us, get in touch today on 0330 002 2111.

So, what are the advantages of switching to SIP or VoIP?

Flexibility – you can utilise your phone system from anywhere in the country. Cloud-based technology means you can answer a call to your work line on your mobile wherever you are. All you need is an internet connection!

Resilience – back up your phone system with an additional fibre line to fall back on should there be an issue on the main line.

Features – call recording and queuing, on-hold features such as music and advertising, and mobile apps are just a few of the useful features that become available when moving to a cloud-based phone system.

Challenger is an expert VoIP provider, with years of experience in getting to know our customers and implementing effective VoIP and SIP systems for them. In 2020 we helped hundreds of businesses move to remote working setups in a hurry!

We assign our customers a dedicated VoIP Account Manager, who is your main point of contact here in the office and will conduct quarterly reviews to ensure that your products are working as they should be.

If you’re looking to move your business away from ISDN, give us a call today on 0330 002 2111 for a no-obligation chat about how we can help. Or, if you want to know more visit