Should I choose an ISDN Phone Line?

ISDN (Integrated Service Digital Network) has been around for many years and has been considered the main solution for businesses when it comes to their communications.

It is a set of digital communication standards for the transmission of voice & data. It consists of physical copper and fibre optic lines connected via telephone exchanges across the world.

There are two types of ISDN phone lines – ISDN2 and ISDN30e.

  • ISDN30e services are more about providing high-performance voice services for business that need a minimum of 8 channels.
  • ISDN2 is similar to a standard phone line although with ISDN2 the lines can be used for phone and data calls.

Advantages of ISDN Phone Lines

  • It has been a proven technology for many years and is very reliable when it comes to the quality of voice calls
  • It is still very flexible and can be incorporated into various systems.

Negatives of ISDN Phone Lines

  • You are limited on phone numbers as they need to be geographical.
  • It can hinder growth plans as it does not easily expand to fit your business growth in terms of new users.
  • It can be costly if you do expand or move offices because of installation cost and also downtime would be an issue to overcome.
  • Limited options to keep inbound/outbound calls in service if ISDN circuit becomes unavailable
  • High rental costs for equipment
  • Some ISDN faults can take up to 72 hours to repair.

A Word of Caution: BT ISDN Switch Off

BT announced in 2015-16 that ISDN Phone lines are to be slowly being phased out. From September 2023 you will no longer be able to purchase any additional ISDN phone lines. Between April and December 2025, there will be a forced migration period before they switch them off.

This means you can still use ISDN phone lines until September 2023 but since it is out-dated technology, it is worth looking at alternatives, now, especially if you have plans to grow.

A number of years ago, something similar happened when SDSL was switched off.

We did our due diligence by telling our clients but one, in particular, did not respond to the urgency and on the day of the switch off, rang us up in a panic. Of course, we did get them up and running again, quickly but there is no denying there was downtime involved, so please don’t leave it until the last minute!

Still have ISDN Phone Lines?

The key thing is not to panic, you do have until September 2023 to purchase any additional lines, so as long as you purchase any phone lines you may need by then, you’d be fine for another few years.

Regardless of when you choose to make a change, it is still a good idea to think about your options are and plan it in, now. The good news is that if you do that now, it is a planned expenditure and not a surprise.

Alternative Phone Line Solutions to ISDN

You need phone connection technology for your phone system to work so with the switch-off of ISDN, you may need to reassess the phone system you have in place.

Below are your alternative options when deciding the way forward from ISDN:

Option 1 - SIP Trunks (SIP Lines)

SIP and SIP trunks is an on-premise or hosted solution for a telephone system that will use virtual phone lines rather than physical wires.

SIP Trunking is fast becoming the best alternative to ISDN as it is cheaper on a per-line basis as it offers flexibility and control over your phone numbers and it’s quick to install.

SIP is suited for medium-large businesses as it can prove to be more cost-effective due to user numbers.

Discover more about SIP Lines

Option 2 - Hybrid Phone System

A Hybrid Phone System combines the different types of connection technology (ISDN, Analogue, Digital and IP) into a single modern and flexible phone system.

Most businesses opt for a Hybrid Phone System when they have ISDN, Analogue or Digital infrastructure but want the advantages that IP brings to the table.

Discover more about Hybrid Phone Systems

Option 3 - Hosted Phone System

The Hosted Phone system is cloud-based which means you connect to it using an internet connection (IP technology) but effectively you are renting the system rather than purchasing your own dedicated system.

A Hosted Phone system is a low-cost alternative to an IP / Hybrid Phone System because you don’t have significant upfront capital costs.

Hosted VoIP is cloud-based and best suited to small-medium sized businesses who are looking for the functionality and scalability of a phone system with no extra maintenance charges.

Discover more about Hosted Phone Systems

Option 4 - IP Phone System

An IP Phone System uses Internet Protocol (IP) technology and the handsets are connected via an Ethernet connection either on a Local Area Network (LAN) or a Wide Area Network (WAN.)

When you choose an IP Phone System, you purchase the phone system for your own use

and you choose where to host it.

Discover more about IP Phone Systems


Continue your Research on the ISDN Switch-off

We have collated a selection of free resources, purely on the ISDN Switch-off. Topics covered include:

Plus many more...

Discover our Free ISDN Switch-off Resources

Found what you're looking for?