Create a more robust broadband connection with PSTN Analogue lines
From broadband and fax lines, to burglar alarm lines, PSTN lines – a standard analaogue telephone line – are still a crucial cog in today’s business world.

PSTN lines are standard telephone lines run over copper and they’re also the same lines that broadband’s installed on, making them a fundamental part of many businesses’ communications infrastructure.

Single PSTN lines can support ASDL and FTTC broadband, both of which we’re able to provide you with here at TSI.  And our highly-trained cabling installation technicians can run lines wherever you need them to be in your building.

You’ll find there are no complicated plans or multiple billing for your PSTN lines, just clear details and single monthly bills, so it’s easy for you to see exactly what you’re paying for.

Use our PSTN line service and benefit from:

– Easy to understand packages.
– Highly competitive pricing.
– Excellent customer service.
– Maintenance and repairs by BT Openreach engineers only.
– Retaining your existing BT numbers.


When linked into a PBX, ISDN2e lines are designed to provide businesses with exceptionally clear, high quality voice calls. ISDN2e can be installed with one number or multiple numbers


These lines are very similar to ISDN2e lines. The main difference is that they provide a larger number of channels, with a minimum of 8.

The future of PSTN and ISDN

The ISDN standard was set in the late 1980’s – at the same time the world wide web was just being invented, mobile technology was finding it’s feet and was still analogue, and urgent business communications were sent by fax.

The PSTN network, including ISDN2e and ISDN30, will be switched off by BT Openreach by 2025.  Every current PSTN or ISDN telephone line will need to be replaced with an IP telephone service – either SIP trunks to connect to a legacy onsite PBX or migrating to a cloud-based unified communications solution such as CallSwitch.

SIP trunks delivers telephone lines using an external data connection for making and receiving calls. In layman’s terms, SIP trunks are telephone lines on your broadband.  This virtual IP-based service uses network data connectivity instead of dedicated fixed line technology methods.

Learn more about SIP trunks

Alternatively, you could replace your onsite PBX telephone system with our cloud-based suite of CallSwitch unified communications. With this approach, not only is there no need for telephone lines or SIP trunks, you’ll enjoy the benefits of a top of the range telephone system that can be used anywhere with business continuity built in.

Learn more about CallSwitch.