Much has been written over the past few years about the rise and stall of IP Multimedia Subsystem (IMS). And while this is still a valid assessment of the state of deployments, vendors such as Ericsson AB (Nasdaq: ERIC), Alcatel-Lucent (NYSE: ALU), and Nokia Networks continue to forge ahead behind the scenes, hoping for a better outcome in the future.

While doing research for a recent Heavy Reading report, "The Ultimate Mashup: Web 2.0 and the Next-Gen Telecom Application Servers," it became apparent that this time around, telecom vendors are focused on developing enhanced hosted application services to increase the overall magnetism of IMS, instead of simply advocating a "build it and the services will come" approach.

One example is the way vendors are portraying IMS as a key enabler for IPTV. The premise is that if you want IPTV, an IMS core is the best option to ensure service integration. This approach started in 2007, but it is becoming increasingly prevalent, especially since Ericsson's acquisition of Tandberg Television . (See Ericsson: Tandberg Is Key to IPTV.)

In reality, however, while IMS may need IPTV, the reverse is certainly not true. IPTV has been deployed for several years without IMS, although conceptually adding IMS into the model does have merit for provisioning, providing quality of service, and integrating other services potentially in a Web 2.0 mashup format. To this end, certain industry groups, such as the Open IPTV Forum (OIPF) , endorse the use of IMS with IPTV as an optional approach.

Unfortunately, solidifying the relationship between IPTV and IMS is also not without significant risk. There are two specific areas of concern.

First, the additional complexity IMS introduces will delay IPTV implementations for network operators proposing an early-to-market strategy. IPTV can be deployed without using Session Initiation Protocol (SIP), which thus does not support IMS integration. Although a movement is underway to harmonize IMS standards with Digital Living Network Alliance (DLNA) home electronics products, some of the initial standards have only recently been completed. This means that fully compliant IMS-IPTV solutions and components, including SIP-based set-top boxes, will not realistically be available for large-scale commercial deployment for at least another year, which perpetuates the impression that IMS lacks maturity and requires additional time to develop. It's also worth noting that IPTV itself supports multiple standards across various forums, which makes IMS integration even more complicated.

Second, network operators must confront the additional expense that IMS injects into the IPTV business case and the possibility that these costs may render their commercial deployments financially unsustainable on a long-term basis. There is already some trepidation about the costs of IPTV without IMS, which has motivated vendors, such as Nokia Siemens, to take steps to implement a hosted IPTV model, allowing network operators to bypass building IPTV infrastructure. (See Nokia Siemens Preps Hosted IPTV.) If carriers are not willing to build out IPTV, how likely are they to implement IMS with IPTV?

This places IMS squarely at the crossroads. If IPTV can be implemented profitably with IMS and gain a foothold contractually in the next 12 months, then IMS has the potential to turn its image around to be seen as finally delivering the goods. But if the flurry of IMS/IPTV deployment activity anticipated in the near future fails to achieve commercial viability and if the finger of blame gets even partially pointed at IMS, then its future becomes progressively more tenuous.

— Jim Hodges, Senior Analyst, Heavy Reading