BT announces date for end of ISDN. Posted by Sally Bailey, 18 May 2015

What does the end of ISDN mean for UK businesses? Read the interview with Richard Holbrook, Bistech’s Technical Director.

BT has announced a target date of 2025 for completing the migration of all ISDN and PSTN customers to IP. Whilst 10 years may feel like a long time, in real terms the migration process will need to begin soon if this timescale is to be met.

And as BT continues to plan for the decommissioning of its ISDN infrastructure, its replacement, SIP, is a hot topic for IT leaders. SIP is now a well-established technology and is the preferred solution for businesses of all sizes, in many ways outperforming ISDN.

Richard Holbrook, Technical Director at Bistech Group plc, gives his opinion on the SIP vs ISDN discussion.

Richard, you’ve seen a lot of industry change over the past 20 years. What does the end of ISDN mean to UK businesses?

Well I believe it’s more the start of something rather than the end of something. ISDN was quite restrictive and SIP provides greater choice and a far more flexible, resilient service than was ever possible with ISDN.

Is all SIP the same?

No, not at all. It’s true that SIP is a standard but the way it’s delivered can vary depending on which provider you choose. An approved, resilient delivery method is fundamental to a successful deployment of any SIP solution.

How does SIP give a business better flexibility than ISDN?

There are so many benefits of SIP technology for businesses. It enables enhanced flexibility, network level monitoring and often returns substantial cost savings. In addition, SIP improves call handling and enables rationalised distribution of lines across multiple sites, improving resource allocation and again saving costs.
SIP also facilitates growth and scalability within a business and with the right provider, is a secure and robust technology for mission critical operations.

How does SIP help with business continuity planning?

SIP enables call routing at the core of the network and calls can be routed to any pre-defined destination, including mobile, alternative site or remote office and across multiple carriers for additional resilience. The redirection of calls happens automatically within pre-defined parameters, minimising downtime.

ISDN is a robust and reliable technology. How does that compare with SIP offerings?

It’s true that ISDN is generally a reliable service but it’s worth remembering that the phase out of ISDN is a certainty, so, over time, BT’s investment in the technology will diminish. The network will no longer be developed so is likely to become less reliable. The number of engineers trained on ISDN will decrease, availability of spares and parts on telephone systems will become difficult to obtain and the support experience is likely to deteriorate. It’s inevitable that, for businesses looking to invest in the future, ISDN will present limited choices.

What should I consider when making the move to SIP?

It’s all about choosing the right partner and making sure you know how many parties are involved in the delivery of your solution.

With some SIP solutions, there can be many providers involved. You may have a single point of contact for reporting a fault but that provider may use a separate hosted service provider, a separate datacentre, another provider for connectivity to site and a different provider for line delivery. Often the ‘behind the scenes’ process goes unconsidered by the customer at the point of committing to a service contract, and the impact is not experienced until there is a fault.

I would strongly recommend that customers take the time to understand how their support contract will work and who is responsible for the service, end to end.

How real are the cost savings with SIP, in comparison to what we’ve been used to with ISDN?

When the market initially promoted SIP as a cheaper alternative to ISDN, the reality was that the cheaper versions of SIP were not necessarily better or even equal to that of ISDN. A service that appears to cost less may be so due to compromised delivery methods.

There’s no doubt, however, that a robust and reliable SIP offering can still provide significant savings. As well as the obvious cost savings on convergence and call rates, multi-site companies no longer need to install lots of lines per site. They can be pooled centrally and used across all sites, saving on line rentals and improving efficiency across the business.

As I mentioned earlier, for companies that have plans to grow and expand, economies of scale with SIP are tangible and can facilitate the ease and pace of growing a business.

And finally, in your opinion, what criteria should be considered when choosing a SIP provider?

I would choose a provider that is selling their own service, end to end, and not reselling somebody else’s. In my opinion, an independent provider that owns its own network, can provide the service across multiple carriers and is also providing the telephone is a logical choice. This will mean you’re not restricted a single provider for resilience. Make sure the service and support you’ll receive matches your expectation and understand the process when there is a fault, who’s involved and who is responsible.