First, for full disclosure: Today’s blog is based on personal observations and discussions based on two years of IMS interoperability events organized as part of my work as technical chair of the NGN IMS Forum. The blog represents my personal views and conclusions and not the views of the forum.

Survey after survey lists interoperability among the top three priorities for successful deployment and implementation of the IMS architecture. With such a large consensus, the interoperability of IMS should take the front seat on the IMS stage. However, as in previous technology deployments, interoperability is a complex issue. The list of technologies which were delayed or never made it commercially includes ISDN BRI, ISDN PRI (delayed), advanced intelligent networks (delayed), Web browsers (still not interoperable) and IM platforms (Yahoo, AOL, Skype and MSN).

The obvious question is, “Why?”

As companies are competing for market share, interoperability is an advantage if you are a competitor and a threat if you are the incumbent. In some cases, incumbent vendors consider the risk of being interoperable larger than the gain, as smaller more nimble competitors can benefit and outsell them.

So who ends up paying for lack of interoperability?

To begin with, we all pay for lack of interoperability in one way or another. If not in actual dollars, then with our time as we try to make our smartphones, laptops, PCs and television sets work together. We get frustrated that WiFi – 802.11 will soon run out of the alphabet soup and we still stubbornly keep our Bluetooth attached to our ear, even if the other party cannot hear half of what we are saying.

Then there is the larger and more substantial cost borne by service providers who, even in current economic conditions, will buy billions of dollars of equipment that will only be able to operate for a couple of years before becoming either too expensive to maintain or altogether obsolete. For example, in the U.S., almost the entire cellular network was replaced by GSM because of early adoption of non-interoperable technologies such as TDMA. So, with so much at stake, one should expect service providers to fight tooth and nail for interoperable equipment.

Service providers are competing for larger market shares and customer retention. They are ready to adopt non-standard technologies that promise a competitive advantage, and this can land them in the largest, most costly trap if they get locked into a vendor, paying premium prices for the technology and support. Furthermore, if vendors do not find enough market, they will cap the development and support, even if they are financially sound. A very recent example of this is Microsoft’s decision to discontinue the Service Deliver Platform announcement.

Even with interoperability at the top of the priorities list, operators and service providers fall victim time after time to the siren song of a short-term tactical advantages, the end up paying in the mid and long term for not pushing the ecosystem hard enough for interoperability.

It is my hope that industry members learn from past mistakes and keep them from being repeated in the future.

Manuel Vexler is chair of the technical working group in the IMS Forum. He is well known for his expertise in voice and multimedia over Internet, bringing more than 20 years of experience to roles such as the CTO of CopperCom and vice president of IMS Interoperability at the IMS Forum. He drove M&A at Cisco, and launched new technologies at CopperCom, AMD, Alcatel (Newbridge) and Nortel.