In my last column I asserted the virtue of an idea whose time has come lies in how obvious the present need appears. Measured by that standard, was IP Multimedia System (IMS) ever a good idea?

 

Let’s face it, IMS is on life support, and it’s about time we pull the plug. The inevitable emergence of mobile networks built from the ground up to handle data makes existing VoIP technologies the superior choice for voice on the mobile network.

 

From the first time I studied IMS I was skeptical. Having grown up in the data world and watching the incremental approach of Ethernet and IP beat out more holistic, control-oriented technologies like ATM, I thought IMS was too complicated. Additionally, trying to solve the litany of problems associated with IMS was too large a task.

 

I struggled to understand its myriad of specifications and acronyms, and kept imagining what people who are less tech savvy must think when they made the same attempt. I carefully listened as senior executives at large network companies pitched their new vision of IMS, but I decided to sit the revolution out.

 

The second major warning sign was the sudden change in positioning by traditional VoIP vendors who, riding the euphoria of IMS hype, started to support IMS in their product lines. These were the same companies that normally took a year to implement a feature request, and now they were marketing a new technology overnight. The funny thing is all of those “IMS” products in their brochures were many of the same technologies we were already using at Cbeyond (News - Alert). The difference was when we bought them they were based on SIP and other VoIP technologies, and then only months later were they IMS products.

 

The final nail in the IMS coffin was the force behind it. Just like ATM, ISDN and other outdated technologies, it was none other than the ILECs and tier-one wireless carriers that propelled these standards. In my experience, the technologies these companies support are not necessarily ideal for the industry at large. As a rule of thumb, I carefully examine such standards before jumping on the bandwagon.

 

Fast forward to 2008 and the need for IMS is less compelling than ever. With true mobile data networks on the horizon from companies like Xohm (News - Alert) and those bidding in the new 700MHz spectrum auction, mobile networks optimized for data and QoS are not far away. And when that day arrives the existing VoIP technologies that took the Internet by storm, especially SIP, will transition into mobile.

 

In fact, we are already seeing this in a number of products, mostly in the fixed mobile convergence space. The logical conclusion is that we’ll arrive at a single protocol and architecture for mobile and fixed broadband environments. It is unnecessary to create an interoperability challenge for voice just to place it on a mobile data network.

 

So, the bad news for some is that IMS is a losing battle. The good news is that just like ATM led to advances like MPLS for IP, so will IMS concepts help mainstream VoIP. The Home Subscriber Server or HSS, analogous to the Home Location Register or HLR in mobile, is a good idea, and I have no doubt the concept will survive in a standalone form in emerging mobile VoIP networks. Perhaps some of the optimizations around hierarchical identity will survive too. But in the end, IMS will fade away while the simplistic power and appeal of IP will prevail.