As easy as it is to connect these days by Internet, cellular, Wi-Fi and plain old telephones, the networks that make all that possible can't...

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NEW YORK — As easy as it is to connect these days by Internet, cellular, Wi-Fi and plain old telephones, the networks that make all that possible can’t communicate well with one another.

Technological standards vary from network to network. The traditional phone system and the Internet, for instance, use completely different protocols.

Now there’s momentum building for a new standard that could enable network operators to bridge these gaps, opening the way for melded services such as simultaneous walkie-talkie and video exchanges between a cellphone and a landline.

If only it were that simple.

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The standard — Internet Protocol for Multimedia Subsystems, or IMS for short — is only a springboard for convergence between future services, not today’s, nearly all of which would need to be adapted or replaced over time to enable them to intermingle.

From simple phone calls, voice mail and call waiting to wireless text messaging and multimedia downloads, most existing telecom services were designed to perform their specific functions as if walled off into distinct silos on the network.

It matters little that most network traffic is now digital. For example, despite the growth of phone services based on Internet standards — known as voice over Internet Protocol, or VoIP — most wireline and wireless calls aren’t transmitted in IP from start-to-finish; calls get converted to traditional phone protocols on either or both ends.

And while a growing number of nonvoice services are IP-based, interspersing their digital packets down a shared network pipe, many applications still need to create a virtual “session,” not unlike the path of a regular phone call, between a user’s device and the network.

IMS attempts to knock down these silos by introducing a common interface for creating sessions. That way, data can be intertwined or bridged across networks to different devices.

Telecom buzz

The technology has been generating buzz within the industry for several years, but recently took a big leap off the drawing board with a series of contract awards by some of the largest U.S. telephone companies.

Earlier this month, BellSouth announced it was buying IMS network systems from Lucent Technologies. Two weeks earlier, AT&T and Cingular Wireless, which is co-owned by AT&T and BellSouth, also signed on to buy Lucent’s IMS technology.

Lucent, still struggling through a migraine-size hangover from the dot-com-telcom bust, acknowledged during its latest earnings report that IMS wouldn’t be generating any meaningful revenue in the near future, but the contracts amount to a substantial endorsement of the company’s technology.

So far, only a smattering of foreign operators and one major U.S. company, Sprint Nextel, have begun deploying IMS, and largely in a way that’s invisible to customers.

Sprint, for example, rolled out a walkie-talkie service, ReadyLink, for its cellphones in 2003 using a pre-standard version of IMS.

But ReadyLink differs little from the non-IMS “push-to-talk” from other cellphone providers, offering none of the multimedia combinations IMS can enable.

When Sprint’s recently acquired Nextel Communications added a new photo-sharing component to its pioneering push-to-talk service earlier this month, it did so without the purported magic of IMS.

Software vacuum

Like most cellphone applications, Nextel’s walkie-talkie feature was essentially created in a software vacuum, programmed with no emphasis on interoperability with other services.

So while IMS might make it easier to write a walkie-talkie program from scratch and add new features down the road, Nextel has to consider the millions of customers already using its very popular non-IMS service.

“You don’t want to fix something that’s not broken,” said Rob Prudhomme of inCode, a wireless-industry consulting firm. Carriers “have a lot of services running before IMS, so their challenge is how to migrate all the services they already have to IMS without incurring a huge cost.”

Likewise, though Sprint used IMS for ReadyLink, the company relied on proprietary technologies for the photo services it launched a year earlier, making integration into a “push-to-photo” capability like Nextel’s more complex.

Such complications make IMS a commitment best suited for major network overhauls — which may help explain why Sprint, AT&T and Cingular are now venturing down that path. All three have placed big-money bets on next-generation network technologies.

Sprint, which is rolling out a speedier wireless-data technology called EV-DO, expects to use IMS to underpin some ambitious new services bridging cellphones and televisions as part of the company’s new alliance with four of the nation’s biggest cable TV providers.

New functions

The new capabilities, expected to arrive by mid-2006, include using a cellphone to view live TV broadcasts, check the program listings, program a digital video recorder, or even watch programs stored on that DVR. Back in the living room, set-top boxes might be equipped for push-to-talk conversations with cellphone users.

Sprint also plans to use IMS to add desktop business capabilities to cellphones.

At AT&T, the IMS foray comes amid a vast upgrade of the company’s local telephone network so that it can deliver television and an array of interactive services using a new Internet-based technology called IPTV.

But in a telling sign, AT&T says IMS will not be the special sauce behind the interactive features when the service first launches in 2006. Likewise, Cingular is making its long-awaited foray into the push-to-talk market with a service based on a non-IMS technology from Kodiak Networks.

“Most equipment has not yet been tested in a real-world setting, to prove that it meets operators stringent requirements for reliability,” analysts at Forrester Research say in new report that predicts IMS won’t be widely adopted until 2009. “Today, carriers like Sprint, that are public about strategic IMS commitments, must deploy non-IMS services until products exist and are proven.”