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Integrated Service Digital Network (ISDN), a telecommunications technology that enables the transmission of digital data via standard phone lines, is being completely phased out by 2025. In fact BT began this process early in 2020 when they stopped supplying ISDN lines.

As a result there has never been a better time to consider switching your communications system to more sophisticated and agile technology.

SIP Trunking Solutions explained

Session Initiation Protocol (SIP) Trunking is a way of delivering voice services over the Internet, often referred to as Voice over Internet Protocol (VoIP). SIP can be supported on the latest IP (Internet Protocol) based phone systems or we can use a Gateway to connect to legacy Private Branch Exchanges (PBX).

BT has announced that it aims to migrate all its ISDN customers onto an IP network. ISDN’s legacy nature renders it inflexible, expensive and difficult to manage.

SIP trunks are the modern alternative to ISDN. Compared to ISDN they allow you to;
• Save money on call costs and line rental
• Make your business appear local in Cities & Countries where you have no office
• Rationalise your voice and data lines
• Deliver Business Continuity
• Better protect your business against Toll Fraud

How iCS can help with ISIP

There are still around two million ISDN trunks in everyday use across the UK. If you’re still using them in your business it’s probably because;
• Your existing PBX can’t support SIP Trunks
• It’s too costly to add to your existing PBX
• Your existing PBX does everything you need and you want to maximise your investment for as long as possible

ISIP is a range of ISDN to SIP converters which allows you to keep your current PBX, whilst providing instant access to all the benefits of SIP.

ISIP is simple to deploy – just un-plug the ISDN cables from the BT service, plug them into ISIP, connect your new SIP service and away you go. ISIP is cost-effective and available in seven different Basic Rate/ISDN 2 & Primary Rate/ ISDN 30 variants – just choose the one that matches your current ISDN trunk capacity.


iCS Communications has a wealth of experience at guiding you through the process and can assist with all your communication system requirements.

Talk to us on 0800 9 77 88 99, email us or to see our product range, please visit our website