Glossary

IP Multimedia Subsystem (IMS) is a technology that defines how to set up advanced services for 3G cellular networks. IMS offers a flexible vehicle for quickly deploying new revenue-generating applications in the network. An IMS core network allows a service provider to deliver identical IP services to fixed and mobile customers, whether the destination is in an IP or circuit-switched (CS) network. IMS-based services enable communications in a variety of modes - including voice, text, location, pictures and video, or any combination of these - in a highly personalized and secure way. As a result, IMS is seen as the cornerstone of carriers' fixed/mobile convergence strategies.

IMS grew out of a group of standards created by the 3rd Generation Partnership Project (3GPP), the standardization body charged with producing globally applicable technical specifications and technical reports for a third-generation mobile system.

IMS is a Media-over-IP network with the following characteristics:

• Uses the Session Initiation Protocol (SIP) as its base signaling protocol
• Based on Internet Protocol (IP) connectivity, and therefore has the potential to provide ALL IP services
• Part of the core network, with interfaces to other subsystems in the 3G network; it can interface with other packet-switched (PS) and circuit-switched (CS) networks
• An architecture for service and call control
• Designed to provide flexible, multimedia services every time, everywhere
• A network that can easily serve roaming subscribers
• Designed to be flexible, robust and secure
• Uses an architecture that will ultimately be used in other networks, such as wireline Voice-over-IP (VoIP) networks, WiMax Wireless networks and Packet Cable networks

RADVISION offers a complete IMS Developer Suite which developers can use to build their own product with.

For more information about IMS, see the IMS overview in the IMS add-on Programmer's Guide for the SIP stack.