The reason why operators want one network to handle all their services is obvious. They want simplicity, cost-efficiency and all the other benefits standardization brings, such as the ability to choose the best component every time, regardless of vendor. But it is no simple task to move all legacy network components to IP without unnecessary cost, without disrupting established business activities and, perhaps most importantly, build a reusable and solid future-proof platform for all services. Operators need stable evolution paths; they cannot afford to take chances. Ericsson says the IMS standard (IP Multimedia Subsystem) is now ready to achieve this.

Niclas Medman, head of Ericsson's marketing program for IMS, says IP-technology has come a long way. "For some applications, IP has already worked well with its traditional best-effort characteristics," Medman says. "But we needed to evolve it further, to make it telecom grade and suitable for real-time services, such as voice and video. We started to look seriously at IP for real-time applications in the late nineties, and from then on, we have taken big strides towards creating solutions on open and stable standards.

"The IMS-specifications are now stable and the first applications are beginning to appear," he says. "What the telecom business has achieved with IMS is to establish a solution that does not force operators to rip equipment out and immediately replace existing network domains. IMS is very much evolutionary and allows them to reuse and maintain existing investments in both circuit switched and IP-technology."

IMS is being standardized in 3GPP, the standards body for GSM/WCDMA, and 3GPP2, the standards body for CDMA. For wireline IMS, the TISPAN standards body is aligning with 3GPP IMS.

Medman says the first applications that truly suit and leverage the IMS environment are now becoming available, and this means they can make money from day one.

"One early application using IMS for mobile networks is Push-To-Talk over Cellular (PoC), the voice service that enables users to easily talk to a group of contacts with very short call setup times," he says. "Wireline networks can introduce a range of services using IMS, including broadband Voice over IP, video telephony, instant messaging and IP Centrex services (virtual PBX)."

Apart from the future cost efficiencies of a common service environment, the ability to create completely new services is the most compelling argument for IMS. Early adopters will gain a competitive edge by offering what is known as the next generation of enriched communication to their customers.

IMS enables a homogeneous service environment using the Session Initiation Protocol (SIP) for signaling, incorporating application servers, call session control functions, home subscriber servers and multimedia resource functions. It allows the creation of services that enhance real-time multimedia by combining different media (voice, pictures, video, text and so on) and different enablers (group management, presence and so on). An example of this combinational capability is to simultaneously share text, pictures or videos with the person you talk to.

IMS means more than converging one type of network into all-IP. It is also the base from which to converge fixed networks with mobile and enterprise networks. It will also establish a common core for the different radio network technologies, such as GSM, CDMA and WLAN. Hence, IMS is the unified network architecture of the future.

So, how far have vendors gone in delivering all these benefits?

"There are already commercial services based on IMS: Ericsson's PoC solution, called Instant Talk, for mobile networks and a range of applications including Voice over IP and IP Centrex in the fixed network," Medman answers. "Additionally, there are trial packages available. An example of one of these covers a combination of services that features sharing of pictures and video while talking."

Implementing IMS is, naturally, a step-by-step process. Ericsson’s strength in this area lays in its end-to-end expertise, extending from consumer aspects to the core and service layers of the network. As a first step, Ericsson will supply IMS nodes and enablers for the specific services. Ericsson systems and services are complemented by Ericsson Mobile Platforms, for core handset technology, and Sony Ericsson, for handsets, and ensure true end-to-end capabilities in the IMS area.

Supported by its Global Services organization, Ericsson has the industry-leading resources to assume responsibility for all phases of the implementation, ranging from business consultancy to integration and management of the complete service. Ericsson's track record in large-scale systems integration speaks for itself: turnkey deployments of mobile and fixed networks for 275 customers in 140 countries during the past 20 years.

"We consider ourselves market leaders, with 25 customers worldwide in different phases of implementing our IMS-based solutions," Medman says.

Facts:

Ericsson's IMS solution offers "horizontal" (or layered) mechanisms to provide common infrastructure and service enablers, such as Charging, Security, Presence, Group- and List-Management, Conferencing and so on, that will be reusable by many services. By introducing IMS and its horizontal service delivery concept based on SIP (Session Initiation Protocol), Ericsson offers a common service delivery infrastructure for many services.

Today, an operator can have a variety of networks, such as GSM/EDGE, WCDMA and Wireline, as well as a mix of transport networks, including IP, ATM and TDM. In mobile networks, packet-data switches (SGSN) are used for data traffic, while mobile switches (MSC) are used for circuit-switched traffic. An IMS domain is now added to this as a cornerstone of network evolution towards a layered architecture with common IP transport.