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IMS Today

By: Richard “Zippy” Grigonis

The great irony of IMS (IP-based Multimedia Subsystem) is that nearly every network operator in the world considers it the “heir apparent” as the blueprint for a common service architecture serving both wireline and wireless networks, and yet deployments continue to creep along. Furthermore, Yours Truly has often marveled at how SOA (Service Oriented Architecture) and Web Services can either be part of IMS or can do a complete end-run around them. Certainly the wildly popular cable triple play service bundles manage to get along without IMS, but optimism for the ultimate triumph of IMS remains.

One company that’s betting on IMS is Tekelec (News - Alert), which dwells among the masters of core multimedia session control and network intelligence. Their signaling solutions enable the interworking of different network applications, technologies and protocols, providing a smooth transition to next-gen networks. For example, their new EAGLE XG, an IMS-friendly signaling and session control platform enables operators to deploy hybrid, next-gen networks (NGNs) while leveraging existing technology investments. The EAGLE XG can host various applications that can be deployed individually or together, such as a SIP Signaling Router (SSR) or a Home Location Register (HLR) that allows operators to flexibly allocate numbers across multiple HLRs in the network, enabling each database to be fully utilized. The platform supports a converged database that enables multiple core network applications, reducing capex and opex by consolidating subscriber and network routing data and eliminating the need to manage, maintain and update databases for each application.

The EAGLE XG SSR overcomes the lack of core signaling and session control in softswitch-based NGNs by serving as a SIP proxy, bridging SIP- and SS7-based architectures to gain access to all routing information. The SSR introduces SIP routing directly into the core network, providing scalability and flexibility for hybrid and IP-centric networks. The system creates a centralized session framework that increases service and network flexibility and lays a foundation for cost-effective growth to support the increasing demand for VoIP and multimedia services.

With a software upgrade, the SSR can also serve as a Call Session Control Function (CSCF) to provide SIP signaling and session control for subscribers accessing IMS services. The app, built to 3GPP standards, enables operators to deliver next-gen multimedia services to any device.

Tekelec’s Assistant Vice President of Business Development, John Lenns, says, “We were part of the recent sixth NGN/IMS Forum (News - Alert) Plugfest. We were pleased to see that this Plugfest displayed a greater maturity in terms of the types of call flow scenarios, centering on more realistic real-world use cases. In previous Plugfests people were doing things such as testing the interoperable connection between, say, the CSCF and HSS [Home Subscriber Server] or the CSCF and a User Element. Now we’re starting to get into some more mature flows, multiple networks, multiple equipment providers furnishing components within the network, multiple user elements, and validating that the authentication and authorization and the charging protocols worked for roaming scenarios, both in and out of networks. So you get the view that we’re getting into modes where we’re validating not only the things that operate, but more advanced scenarios. That was really pleasing to see, and it was pleasing to observe how smooth everything went. There are always new discoveries. The beauty of the Plugfest is that everyone interprets the standards in certain ways and you get together in a non-threatening environment and you do you testing and we all learn about what’s the common technical interpretation and you go from there. The Plugfest was a good experience for us, and we’re still committed to continue participating in the Plugfests.”

“We still consistently believe that IMS will continue to take time to roll out,” says Lenns. “IMS continues to take time to roll out. The rollout will be not so much a total forklift of the network, but rather a gradual appearance in an evolutionary manner. We’ve already seen the evolution of the legacy TDM signaling network to an IP-based signaling network via SIGTRAN. We see a continued evolution from that into SIP [Session Initiation Protocol (News - Alert)], and we’re obviously adjusting that space with our SIP signaling router product. And then, there’s a gradual evolution from that to the CSCF functionality. So we do see a gradual rollout of IMS and I think that will be the result of the ‘pull’ of the desire to rollout new applications and capabilities to subscribers, and to be able to accurately track usage and charge for those. As the new capabilities need to roll out to the subscribers, that will further evolve the network, so as I say, it won’t be a forklift upgrade, but a gradual evolution.”

In furtherance of IMS testing, Tata Consultancy Services (News - Alert) (TCS) has developed lab-tested tools and frameworks on IMS, such as their IMS Development Tester – an IMS Test Suite development based on 3GPP IMS conformance specifications, application development experience. For the record, they also offer the iConverse IMS Application – a next-gen app that helps users understand the topic being discussed on a live call in detail through live feed on an Instant Messenger. Finally there’s the IMS-based IPTV (News - Alert) Application – which has features such as SMS on IPTV and call receiving capability on IPTV.

Based on deep product engineering engagements with equipment vendors (including test and measurement vendors) TCS has acquired early access to and expertise in upcoming technologies. As such, TCS is able to efficiently service large carriers and EVs to overcome their challenges in the wake of technology churn.

Can IMS “Bear It”?

IMS is supposed to “de-silo” applications, making them easier to develop and deploy and thus advancing the world of Operations Support Systems (OSS). To find out, Yours Truly talked with a major player in the OSS world, VPIsystems, whose OnePlan integrated network planning system enables service providers, systems integrators and manufacturers to design, plan and implement their transition to a next-gen IP-based network.

Robert Smithline, Senior Director of Next Generation Strategy at VPIsystems, says, “IMS is an important part of next-generation networks, particularly on the wireless side. But it is not the de facto next-gen solution for wireless or wireline carriers. It has been very slow to develop. They’ve been working on it since 1998. When things are slow to develop and deploy, it’s a bigger challenge to get adoption. A good example is IPv6, which took so long to develop that IPv4 enthusiasts came out with so many extensions and workarounds that it solves many of its own problems. Likewise, since IMS has been slow out of the gate, there are some other technologies out there that may supplant it as the next-gen solution for delivering services, such as Naked SIP or Generic Access Networks [GANs]. But there are lot of IMS deployments out there and there will continue to be because it solves problems for a lot of carriers.”

“IMS is unique in that it shares a bearer network but it controls the way bearer traffic is run,” says Smithline. “This works very well into the way we handle network planning. We consider networks as a single entity, and every part of the network affects every other part. So, you can’t look at your IMS design in a ‘vacuum’ and just plan your IMS network independently, because changes in your IMS network will impact every other part of the network. Do you want to place your application servers directly in the middle of the core? Or do you want to distribute them on the edge? As you move around the control devices within an IMS infrastructure, it greatly affects where the bearer traffic is going, and it will impact every layer of the network design. And of course complicating matters is that the standards groups are trying to insert functionality for everyone in the specifications. IMS could have been deployed a whole lot earlier.”

“As it is, when planning an IMS network, there are many things to consider,” says Smithline. “First, of course, there is the underlying bearer network, and how your plan for IMS will impact the underlying bearer network. And then there’s the equipment modeling for all of the different pieces involved in the IMS infrastructure. All of those ‘pieces of kit’ have to be dimensioned properly to deliver the services that you want. These are typically revenue-bearing services. So they tend to have a higher priority in the planning groups than some other things might. And each of these has different thresholds and different build levels that the groups want to attain, as well as a certain tolerance for redundancy. So when planning for your IMS network, it’s very important to consider the kit involved in it, and to have a tool that takes into account your business rules when it tells you the right time to build. It’s not just the economy. Wireless has been on the ropes for a long time as far as the amount of capex providers are willing to spend. Senior management expects just-in-time bills. The planners are also expected to have a network that is resilient and stands up to new growth. Given the way wireless networks and even wireline networks have been growing over the past five years – and given the way we expect them to continue growing over the next five years – there’s a lot of risk involved in the network design if you don’t have a proper planning tool.”

“Every estimate you see out there, seems network bandwidth growing by at least 50 percent a year, and probably more for the wireless carrier, because they’re making a big leap from 3G to 4G. So you need a lot of good marketing data to really drive your network designs and add input to your planning tool.” IT

Richard Grigonis is Executive Editor of TMC (News - Alert)’s IP Communications Group.


The following companies were mentioned in this article:

Tata Consultancy Services – (

Tekelec – (

VPIsystems – (

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