Celebrate Your Independence From ISDN

Monday 4th July 2016 • 3 min read
Billy Law-Bregan, Communications Officer

Because the clock is ticking for ISDN.

After much deliberation, BT has announced the date ISDN will cease. BT has a strategy to achieve its termination by 2025, with a full ten-year plan to match. However, some observers do not think that the allocated time slot is feasible in light of the current number of ISDN users.

Ofcom’s 2015 Communications Market Report states that the decline in fixed voice revenues accelerated in 2014 by 2.6% (£0.2bn), from a decline of 1.4% in 2013. The number of fixed-originated calls fell by 12.6% to 80 billion minutes during 2014, whilst mobile calls increased 2% to 137 billion minutes.

These trends are set to increase exponentially, but the Ofcom report indicates that:

“Despite rapidly declining fixed call volumes, there has only been relatively little change in the number of UK fixed lines (including PSTN lines and ISDN channels)”.

This indicates there is a large number of ISDN users who have yet to realise the cost benefits and communications advancements that SIP-based technology can allow.

One of the primary benefits of eliminating ISDN and moving telephony to a SIP-based platform is the removal of costly Basic Rate Interfaces (BRIs) and Primary Rate Interfaces (PRIs) subscriptions. Cost benefits are of course the primary driver for most businesses and these are echoed in the removal of any investment in PSTN gateways or additional line cards as companies expand. Edge devices offer a low investment path in adding new lines as they are typically cheaper per line than the corresponding PSTN gateway. It makes logical sense to optimise the utilisation of bandwidth by delivering both data and voice in the same connection.

The use of SIP trunk technology also allows for the flexible termination of calls to preferred providers; calls to anywhere worldwide can be made for the cost of a local one. For businesses with multiple sites and locations, the redundancy in dealing with multiple service providers and links can be an argument that it is less expensive to purchase and administrate an IP-PBX than the traditional PBX.

The cost effectiveness of a SIP trunk is such that by replacing an existing PSTN gateway/PRI installation with an edge device/SIP trunk, ROI may be achieved in a matter of months. For new installations, a SIP-capable edge device is most often a smaller investment than a PSTN gateway, making that investment cheaper.

Now is the time to look at becoming independent from ISDN and moving to a fully SIP-based communications platform. With BT’s ISDN countdown clock ticking away it is a move that every company currently with ISDN channels is going to have to make anyway.

So, are you celebrating yet?


If you have any questions regarding this blog or require further information on SIP Trucks or Unified Communications please get in TOUCH.

Discover Think Colocation is for you?

Purpose built demo suite

All Aboard the Mobile Solutions Centre