An integrated network for telecommunications carriers that uses the IP protocol as its foundation for packetized voice, video and data. Supporting voice over IP (VoIP) in all its flavors (SIP, H.323, MGCP, etc.), the IP Multimedia Subsystem (IMS) is designed to interface with the PSTN and provide traditional telephony services such as 800 numbers, caller ID and local number portability. Converged Wireless and Wireline Part of the 3GPP project, the IMS was conceived to offer full support for every type of communications session in today's world whether over wireless or landline, including instant messaging (IM), push-to-talk, videoconferencing and video-on-demand (VOD). It is the 21st century initiative for carrier networks supporting IP convergence. See LTE, 3GPP, VoIP and IP on Everything.