The Stack Archive Expert View

ISDN: “I Still don’t need it.” The truth is you’re right.

Mon 15 Feb 2016 | Ross Warnock

With BT planning to completely discontinue ISDN, we ask when’s the right time to deploy a superior solution?

No matter how long you spent at engineering school or how specialised you became in a particular field, there is one golden rule that holds true across all technical disciplines: “If It Ain’t Broke, Don’t Fix It.” This expression of hard-earned wisdom advises against seeking out trouble for you will surely find it.

That being said, it is incumbent upon any technical decision maker to determine when is the right time to replace what appears to be a perfectly adequate technology, and more importantly how to implement the new technology successfully so that its inherent benefits can be maximised.

For example, ISDN (Integrated Services Digital Network) remains widely entrenched in British businesses despite being superseded in almost every respect by an alternative cost-effective voice-technology that offers improved flexibility and reliabilty. There are still more than 2 million active ISDN channels in the UK and BT has announced that it will discontinue its ISDN services completely by 2025. Yet some businesses remain reluctant to migrate away from this outdated technology.

It is hard to think of a good reason to persist with ISDN infrastructure, even if the capital investment required to implement it has long been written down. In terms of operating cost, scalability, reliability and flexibility, SIP (Session Initiated Protocol) -based telephony solutions are vastly superior. One is forced to conclude that people remain loyal to the old methods for bad reasons: fear of change, reluctance to disrupt existing practices, a resistance to explore new possibilities.

It is particularly ironic when one considers the hesitancy with which many approached deploying ISDN when it first appeared in the 1980s. Older hands may remember when the acronym was said to mean I Still Don’t Need It, Innovative Services we Don’t Need or It’s Still Doing Nothing!

Today, businesses have to ask themselves whether they do I still need it, and is it still innovative enough?

There are many good reasons for migrating away from ISDN to SIP-trunking. Line rental costs can be between 50 and 60 per cent cheaper. Call costs can be up to 30 per cent cheaper, and furthermore, many providers offer inclusive minutes as part of their regular monthly fee. However many business are now discovering that service providers may choose to keep them on their existing ISDN package as it is a more profitable solution for the encumbent provider.

It’s a fact that SIP-based telephony solutions are inherently more flexible, scalable and resilient than ISDN. Capacity can be increased and decreased easily as and when it is required.. Faults on ISDN lines often mean long delays while faulty infrastructure is repaired. With SIP-based telephony, resilience is built into the system so that voice-traffic is instantly rerouted to an alternative line or calls can be redirected immediately to different locations or even to mobile phones.

So why are so many businesses still reluctant to make the change to a more cost effective, flexible, scalable and resilient technology? No doubt the pain of transition is putting some people off but that is a bullet that will have to be bitten sooner or later, now that the demise of ISDN has been given a deadline.


True, the move will involve some disruption to business, the inevitable auditing of existing systems, the documenting of backup plans and the scoping out of the potential benefits likely from an upgrade. However these are the sort of things that any business should have in place as part of a business continuity plan.


Here’s the challenge: can you think of one good reason to keep ISDN ahead of a technology  that’s proven to be better? If you can, then maybe you should consider holding off change for a little longer, but remember: ten bad reasons don’t outweigh a single good one.



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