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January 2007
Volume 10 / Number 1

Why Enterprises Should Care About IMS

By Tony Rybczynski


IMS is hot and IMS-based services are being introduced by service providers around the world. IMS Magazine, launched earlier this year, is a sister publication of Internet Telephony. IMS, the IP Multimedia Subsystem, is a set of architectural standards that is driven by a vision that delivers multimedia end user services, independent of access service delivery (wired, wireless, cable). Through IMS, service providers will be able to accelerate service deployment to consumers and businesses alike, while lowering deployment costs, both achieved by incorporating a set of pre-integrated enablers and open interfaces. Great vision for service providers, but why should enterprises care, since they are focusing on SIP, Web Services, and Service Oriented Architectures (SOA) to achieve similar objectives in the context of their own environments?


The IMS Architecture

Service providers have traditionally operated in silos: multiple networks each with their own set of services and management systems. For example, as consumers, we may subscribe to multiple services, have multiple phone numbers and email addresses, learn multiple ways to forward a call, have to manage multiple inboxes and receive multiple bills. Wouldn’t it be nice if services were offered under a single profile and regardless of location, connection type, or device? Wouldn’t it be neat if your PC, phone, cell phone, and TV were converged into a single experience, offering new modes of personalized communications and services? At the consumer level, this is exactly what IMS is trying to do.

In more technical terms, IMS is an architecture that takes a layered approach and separates transport, session control, service, and applications. It is an access, protocol, and device agnostic architecture that allows convergence across wireline, cable, and wireless networks. It provides service-independent management of user profiles, and supports service enablers such as presence, location, and contact list management. It will enable a new generation of rich voice, video, and multimedia services across both wired, cable, and wireless circuit and packetswitched networking infrastructures.

This architecture is heavily reliant on SIP, the Session Initiation Protocol, for all session signalling between IMS entities. SIP is an industry standard, is media agnostic, and has extensive negotiation capabilities for point-to-point and conferenced multimedia communications. This is the same protocol that is forming the basis of Unified Communications systems. IMS also uses Web Services and SOA (some would say IMS is simply the service provide element of a broader SOA) at the application/ service creation level and enables interaction with 3rd party applications.


What’s in it for Enterprise?

Enterprise IT investments must either lower cost, improve productivity and business effectiveness, or improve customer service and/or grow revenue. The end game is the real-time virtual enterprise, whose operations are seamlessly, securely, and instantly supported across employees, customers, partners, and suppliers.

IMS-based services offered by enterprise-focused service providers can extend and complement enterprise capabilities into the public domain for users who have both public and enterprise identities. They can offer Find Me/Follow Me via SIP-enabled personal agents for presence, mobility and personalization, and enrich or enable enterprise applications through location-based services. For example, fleet management resource applications implemented in the enterprise services can be enhanced through location and presence capabilities of the public network. Emergency response teams can communicate more efficiently through location and presence awareness, and take advantage of the security and multimedia capabilities of the IMS network. Federated systems can be extended across large and small business and various levels of government.

Most service providers realize that a gating factor in successfully delivering IMS-based services to enterprises is security. This includes endpoint security that authenticates users no matter how they connect to the network, scans the devices used to ensure compliance with security policies, and authorizes access to application and services. Endpoint security is a key enabler of federated identity systems that control communications among enterprises. Other dimensions of security include perimeter security — establishing trust domains and controlling ingress and egress across domains — and core network security for viruses and other forms of attack. Communications security is also a requirement to encrypt signalling and media for users connected directly to IMS and running over a public IP network, or remotely connected over the general purpose Internet. By implementing these capabilities across an IMS network, service providers can significantly offload the enterprise IT security burden across an increasingly mobile and distributed environment.


So Why Should Enterprises Care?

Let’s conclude with three key points. Firstly, IMS is primarily intended for service providers and will not generally be implemented in enterprise networks; on the other hand, enterprise applications can become more effective by being extended through enterprise-oriented IMS-based services. Secondly, IMS represents a significant notching up of the industry commitment to SIP as the lingua franca of Unified Communications, providing more options to enterprise customers. Thirdly, enterprise investments in Web Services and SOA will be extended to communications- enabled business processes, not just across the enterprise but also across IMS-enabled federated systems to partners, suppliers and ultimately customers.

Tony Rybczynski is Director of Strategic Enterprise Technologies at Nortel. (quote - news - alert) He has over 20 years experience in the application of packet network technology. For more information, please visit


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