IP Multimedia Subsystem (IMS) specifications were first released by 3GPP – the association of telecoms standards bodies – as part of the next-generation networks (NGNs) framework in 2002. IMS was touted as the architecture to take telecoms forward into a world of convergence and enable the fast development of new services.
Six years later, the predicted mass adoption of IMS hasn’t happened and the initial hype has given way to disillusionment about its potential and relevance in an increasingly Internet-dominated world. Concerns about the business case and new ways of delivering new services are making people wonder whether it will ever be deployed on a large scale.
Potential benefits
3GPP’s vision for IMS is to enable the delivery of any service over any IP-based network, irrespective of access technology. IMS is intended to act as the ‘network glue’ that will provide the following benefits:
- a common service platform from which to launch new applications quickly
- developer-friendly application interfaces so that service elements can be re-used across multiple services
- open interfaces enabling operators to choose the best-in-class and/or the most cost effective equipment elements
- standards-based interfaces to allow interworking between networks including legacy networks
- a guaranteed quality-of-service environment with multi-session control (which cannot be guaranteed in current Internet architectures)
- a more secure environment than the open Internet
- the ability for the operator to maintain control of session-related billing
- SIP-based architecture, compatible with developing next-generation multimedia (combined voice, data and video) applications and fixed-mobile convergence.
IMS’ expectations reached their zenith in 2005, but now it seems that publicised deployments are struggling to advance beyond small-scale trials that in some cases haven’t left the test laboratory. The waters are muddied further by the use of non-standard interfaces, which call into question whether these deployments can even be described as IMS compatible. This may not be critical to the initial service launch, but may cause issues later when more services or other vendors’ equipment are introduced.
In the UK at least, IMS still has the potential to play a key role. Legacy voice equipment and systems have not been replaced on a large scale as quickly as was anticipated. When the replacement does gain momentum – not least because legacy equipment will soon become obsolete and impossible to maintain – IMS could be used to create an environment from which operators can generate new applications and services to arrest revenue decline, caused by price erosion and fixed-mobile substitution.
Inhibitors
However, operators are anxious not to degrade the quality of their services, which is always a possibility when introducing new technology, particularly for voice, which cannot tolerate latency and where quality is a key differentiator over Internet-based services. This makes operators wary of mass deployments and leads them to take a conservative approach.
Justifying the business case is proving to be a stumbling block too. The many functional aspects of IMS and the price premium placed on new technology can make the business case difficult to justify if it is based on potential revenues from one or two applications. The true cost benefits of IMS arise from being able to launch tens or hundreds of applications cost effectively. This is a big leap of faith for operators. In the UK, BT is taking a lead in this area with its Web21C initiative, but it is still in the early stages.
And the open nature of the IMS architecture is not proving to be as advantageous as originally envisaged – that is, allowing the operator to choose best-in-class and/or the most cost effective components for each element. In practice, while the technology is immature, this approach can be an integration nightmare and is too risky, especially for smaller operators who tend to plump for single-vendor solutions.
The Internet threat
Proponents of Internet-based applications see IMS’ structure as an unwieldy relic, based on the principles of a vanished age. They see it as over-specified and at odds with their vision for applications. For this sector, web-based applications are the way forward, building on the likes of Skype, MSN and Grand Central (owned by Google) and incorporating others, such as social networking, in new service mash-ups.
The Internet players are innovative and are quick to get new offerings to market, but is this the only route for all communications? Internet-based applications have proved very popular, but they have yet to demonstrate the reliability and interworking levels that characterise telco-based services.
IMS’ future
In generating new service revenues, traditional operators’ reputations for reliability with a high degree of interworking will protect their revenues for a time, but they cannot rely on this differentiation indefinitely as Internet-based companies will address these weaknesses.
If IMS is to achieve its potential, it faces some stiff challenges and proponents need to:
- obtain the buy-in of their company to the business case for IMS within an NGN framework
- develop an implementation plan for deploying new network infrastructure and retiring the existing network
- manage the deployment of the network upgrade and retirement programme, while maintaining a reliable and robust network
- develop a business and technology environment that encourages in-house and third-party application developers (including Internet-based competitors) to bring their ideas and development skills to the operator’s network.
