Most independent telephone companies in the U.S. neither partake in nor care about what happens in the 3G Partnership Project, the international standards group that developed the specifications that form the massive and much-hyped IP multimedia subsystem standard.

To anyone who has witnessed the evolution of the IMS movement in recent years, it also might seem that the standard primarily addresses technology issues that only are of concern to the largest telephone companies — the ones that want to pursue fixed/mobile convergence with their national wireless operations, or have christened multi-million-dollar projects introducing IP network elements and session initiation protocol (SIP) functions into their networks.

But according to vendors addressing the independent telco market for IP technology, the independents are very much interested in the IMS standard — or at least parts of it. “It's a complex picture, this standard, and independents are interested in certain aspects of it,” said Martin Taylor, vice president of product management and technology strategy at MetaSwitch.

Far from deploying an end-to-end, integrated IMS infrastructure, smaller telcos are more likely to be interested in deploying some specific IMS-based network elements that can help them address some real-world business concerns, including competition from VoIP and wireless service providers.

Very large, inter-related service providers like AT&T, BellSouth and Cingular Wireless are deploying IMS to smooth the network and service integration, as well as converged service creation. Some of this is driven directly by competitive pressure, but the migration also is driven indirectly by the plethora of broadband access methods that now exist and the efficiency to be gained by having them integrated with an intelligent IP subsystem at the network core.

Given such grand network designs, some people might wonder if the smaller, less multi-dimensional independent telcos really need IMS. However, it all boils down to the competitive pressure mentioned by Taylor. “If you are worried about that kind of competitive encroachment, one of the things you can do with IMS is create more sticky services,” he said. Telcos interested in IMS-based services can start by deploying SIP application servers to augment basic call control functions to include more features like IP-based conferencing, advanced call forwarding and applications based on user location, among others.

If you have deployed SIP servers, you haven't deployed IMS, but you have adopted a network element central to IMS infrastructures, along with the signaling protocol that is itself central to IMS.

“If you equip an independent telco with that much, then you have given them a weapon they can use to fight back against the competition,” Taylor said. And while IMS may not reduce operational expenses, it provides a standard of establishing open interfaces between network operations, service creation and service delivery. As a result, and independent telco can use IMS to improve the service delivery process by allowing service providers to build or integrate Web-based service portals into their offerings.

Vikram Saksena, chief architect for Sonus Networks, added that the implementation of SIP proxy servers sets independent telcos on a course “to converge to a network architecture with as few protocols as possible. The smaller players will start with a simplified version of IMS. Then they will have some core components and can pursue IMS with a gradual network migration in mind,” he said.

While many of the smaller independent telcos may still operate circuit-switched networks, as a market, the independents are in fact moving to the packet switching world along with everyone else. At this point, the efficiency benefits of packet-based infrastructures are well understood, with many projects completed and many others under way. IMS is the next step in transforming a telco's network to better address a changing competitive service environment, but in some ways, it's more complex than the previous transition to packet switching.

For one, IMS consists of multiple elements deployed across an entire subsystem. Also, the standard itself is a huge document, with most IMS specifications issued by the 3GPP in two major releases — Release 6 and Release 7, the latter of which was completed recently. In addition, although SIP is a single protocol for dynamically establishing different kinds of communications sessions, many telcos that heretofore haven't had SIP in the networks will need a tutorial on what SIP is capable of and how to manage SIP sessions.

“There is a lot of guidance and education that is still needed,” Saksena said. “We need to keep it simple. [An independent's] service and business models might not be able to absorb complex solution changes the way the larger telcos can.”

In this instance, a vendor can help a small telco sort through the IMS clutter to find the parts that in the near-term may be worth more than the IMS sum. For instance, while the IMS standard includes the voice call continuity (VCC) specification, which will be the basis for future fixed/mobile convergence services, a small telco faced with competition from mobile substitution may not need to wait for VCC (which requires VCC-enabled handsets that, for the most part, aren't market-ready). Instead, a SIP-based find me/follow me call control solution may do the trick, said MetaSwitch's Taylor.

“We've have seen some demonstrations of extraordinary technical virtuosity with IMS, but if I'm a subscriber, I really don't care about all of that,” Taylor said. “Just give me a service I can use.”

Vendors such as MetaSwitch, Sonus, Genband and Stratus Technologies recently have been making overtures to the independent telcos to help them understand and adopt IMS. The latter two companies separately carried out acquisitions within the last month that bolster their IMS-compliant offerings to independents, with Genband acquiring BayPackets and Stratus buying Emergent Network Solutions.

For its part, Sonus recently forged an IMS-focused partnership with Embarq Logistics (formerly Sprint North Supply) that taps into that company's well-established distribution channels in the independent telco market. “That partnership is a realization that there are so many of these types of companies that are out there and may be ready to pursue these projects,” Saksena said.

Meanwhile, IMS itself continues to be a technical work in progress. This summer, Verizon Wireless unveiled the culminating proposal from its own two-year, behind-the-scenes review of what it said were gaps in the existing IMS standard. In Advances to IMS (A-IMS), the carrier proposed several additions, including support for both SIP-based and non-SIP applications in an IMS environment, more security functions and other new elements.

Having support for non-SIP solutions will definitely help independent telcos that may face several years of straddling between legacy and next-generation network environments. However, A-IMS may not have much to specifically offer smaller independent telcos. Both Taylor and Saksena acknowledged that the IMS standard can benefit in the long term from the additions and clarifications proposed in A-IMS, but Taylor added, “The gaps that Verizon Wireless is looking to fill with A-IMS are only of issue for very large, very complex networks and not so much for independent telcos and rurals. They are more concerned with how a given SIP device will interact with call services.”

ONLINE

For more on Verizon's A-IMS proposal, read “A-IMS breaks Verizon's silence” on the Independent one-stop on our Web site. www.telephonyonline.com/independent