The IMS Common System contains the common IMS functions required for applications combining voice and data (convergent services) to be delivered to users, irrespective of the access they use. 

It provides telecom-grade operations of IP-based services, and the availability, reliability, and scalability of Ericsson's Telecom Server Platform.

The IMS Common System utilizes a horizontal architecture built with:

• Core nodes that supervise IMS networks and manage routing and sessions
• Service enablers for general use by all applications, offering a cost-effective way to introduce new applications
• Inter-working nodes that tie the IMS network into its environment
• Support nodes that offer the functionality required for provisioning, management and charging.

Ericsson is the undisputed market leader in IMS with a market share of 48 percent (ABI Research, March 2008).  Ericsson IMS Common System forms the basis for each of the IMS solution that has been contracted.

The IMS Common System's horizontal architecture enables easy introduction of new technology in the network. Service enablers for common functions can be reused, while each layer can evolve independently to reflect market and technology developments.The base for both wireline and wireless applications, the IMS Common System paves the way towards fixed-mobile convergence and the all-IP vision, while delivering revenue-generating opportunities.

The IMS Common System is the basis for innovative, converged services that generate revenue and attract new subscribers.

It can be combined with Ericsson-developed, standardized applications such as Push to Talk, weShare and Multimedia Telephony or form the foundation for applications developed by any vendor. This secures the flexibility and short time-to-market required to fulfill the need for new services and enriched communication experience. Based on 3GPP, 3GPP2 and TISPAN standards, and using Session Initiation Protocol (SIP) for control signaling, applications run on the IMS Common System are interoperable – an acknowledged cornerstone of mass market acceptance

Realizing the potential of IMS requires planning and a structured approach to implementation. Ericsson's offering includes consulting, system integration, managed services, network deployment and integration, and education and support services to ensure IMS applications have the interoperability, quality of service and security needed to ensure mass market take up.