IP Multimedia Subsystem (IMS) has received a lot of attention in the industry this past year. IMS refers to an IP-based core network for use with multiple access networks to provide a converged service to wireless, wireline and cable subscribers.  

Initially, IMS standards were defined for 3G UMTS (Universal Mobile Telephony System), which is the next generation of GSM cellular systems. CDMA standards organization has chosen to utilize these same IMS standards as a base to build upon for their 3G CDMA-based cellular access. Additionally, PacketCable, an industry association made up of Cable service providers and cable infrastructure vendors, is working on their next generation of standards, namely PacketCable MultiMedia (PCMM) 2.0 specifications, and they are specifying cable access as another method into an IMS-based core network, thus enabling further convergence.  

Large Tier 1 wireless and cable operators have already announced agreements to interconnect their services to offer a converged service for their customer base. It truly is an exciting time in the Telecom industry. Furthermore, wireless broadband access is also being added to this IMS model. WiFi access along with WiMAX access networks are being designed to access an IMS core network to provide market differentiating, leading edge, single number services to end users.  

The IMS core network uses SIP (Session Initialization Protocol) for call control to pass control of the call/sessions between different call handling elements within the IMS core network, making it a very flexible network on which to build new, exciting services. The core network is often shown as a layered network consisting of a transport layer (media like voice, video, data, etc.), call control layer and applications layer. A key benefit of the IMS core network is the use of a common application layer while reusing common transport and call control layers to provide multiple services to users across multiple access networks. The use of a common core network allows operators to provide their users with access to common applications across divergent networks, while lowering their CapEx and OpEx for increased profitability. AudioCodes’ Mediant™ family of media gateways has been designed to become the heart of media/bearer processing within these IMS-based networks, providing the appropriate voice processing required to complete and handover calls between divergent access networks and the existing PSTN, if required. These divergent access networks typically require different vocoders, protocol and signaling support, so maximizing voice quality will naturally dictate minimizing the number of vocodings required in a given call and naturally increase the number of vocoders required to be supported on a given IMS media gateway.  

AudioCodes’ Mediant™ media gateways have been inherently designed as IP-based systems to support wireline (carrier VoIP & enterprise VoIP), wireless (CDMA, UMTS, GSM, WiFi, & WiMAX) and cable access networks, making the transition to a combined, converged IMS-based core network a relatively simple task.  

AudioCodes’ media gateways currently support existing wireline, CDMA, UMTS, GSM and cable vocoders and additional vocoders are being constantly added as required, making these Mediant™ gateways an excellent choice to fulfill the current and future needs of the IMS core network.