SIP and ISDN Can Work Together

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When SIP trunks were launched several years ago many were quick to hail them as the death knell for ISDN. But Mark Curtis-Wood, Head of Network Services at Nimans says ISDN still continues to hold the upper ground and he argues that the two ‘rival’ technologies can in some circumstances complement each other and work together.

“From my perspective we are certainly seeing more traction with SIP now. There are estimates of some 5 million ISDN lines out there compared to about 180,000 SIP trunks in operation. We are still really scratching the surface but in the last few months we’ve noticed a much larger take-up in line with all the market projections which indicate quicker deeper growth throughout 2011. One major factor is the development of powerful broadband products which generate a more reliable service such as Fibre To The Cabinet – as well as wider bandwidth available at a more affordable cost. The cost of true ISDN replacement then becomes more of a reality.”

How to bridge the gap between ISDN and SIP comes down to a couple of factors according to Mark. “The key thing is educating resellers to understand the true benefits of SIP other than cost savings -selling it as part of an overall solution that takes into account a client’s needs and the added value that brings. The other gap that needs to be bridged is people trusting IP technology over standard copper that’s sat in the ground. It’s a more historical obstacle that’s entrenched in many people’s minds – that copper is more reliable than an IP circuit. In most cases IP still relies on copper but there’s a perception that ISDN is going to be more reliable and provide a longer tem solution.

People are more familiar with ISDN, they trust what they are used to. IP networks are getting more reliable, it’s just getting over the mindset. Ideally you need quality dedicated broadband that’s only carrying voice. In the early days there was a degree of misinformation about the benefits of SIP. Use a cheap broadband network with poor contention rations shared with lots of other applications and internet service – and inevitably you are not going to get a great experience. It’s about laying the right foundations.”

Mark emphasised: “I think one of the biggest changes we are going to see is when businesses re-evaluate their whole ISDN infrastructure. There’s a transitional period going on today. I think the tipping point for SIP will come this year or next. It’s not rip-out and replace but rationalisation of ISDN and running SIP alongside to complement each other. There’s still a good case for having some ISDN in a business but in reality most companies don’t need all their channels of ISDN. In many cases it would be better to have a split of ISDN and SIP to give more diversity and a bit of protection should anything go wrong.”

Mark points out some key sales tips for resellers to deploy when assessing the benefits of SIP. “It’s a more flexible solution. If a company moves office they can take all their numbers with them. From a business continuity point of view you don’t have to change all your numbers. You could be anywhere in the world and are no longer tied to a specific geographical location say 0121 for Birmingham. Some businesses are looking to switch from 0844 and 0845 numbers and gain more of a local presence in a specific area but don’t want to have an office located there.

“Disaster recovery is another big area now. If an ISDN line goes down you lose your communications but with SIP you have the ability to individual divert calls using a web portal to any number required say individual DDI’s to mobile numbers or other offices.

In addition cost savings also play a part. The cost of increased quality bandwidth is coming down which makes using SIP much more viable. The other big advantage of SIP is that it can reduce excess construction charges. SIP is often much cheaper for new installations and is more flexible than ISDN. Many ISDN contracts are based on two and three year periods but with SIP it can be on a 6-12 month basis. You can also increase and decrease the amount of trunks for more flexibility.”