IMS is a unified network architecture that enables the delivery of converged services and a consistent user experience, regardless of the access technology (wireline, wireless, cable, etc.). Initially, IMS referred to standards that were defined for 3G UMTS (Third Generation Universal Mobile Telephony System), known as the next generation of GSM cellular systems in the 3rd Generation Partnership Program standards (3GPP) organization. UMTS defined the possibility of having a common IP core network that could be used for voice, video, data and additional services.

IMS makes considerable use of two controls; SIP as the services call control and H.248 as the transport call control. This combination of standard-based protocols, amongst others, provides a more flexible, powerful core network upon which to build additional services.

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.

Subsequently IMS has been chosen by multiple standard organizations as a building block for additional access networks. An example being, the CDMA standards organization (3GPP2 – Third Generation Partnership Program 2), has chosen to utilize these same IMS standards as a building block for their 3G CDMA-based cellular access. PacketCable, an industry association consisting of Cable service providers and cable infrastructure vendors, is working on their next generation of standards, namely PacketCable MultiMedia (PCMM) and PacketCable 2.0 specifications, designating cable access as another method into an IMS-based core network, thus enabling further convergence. Fixed network standards group ETSI/TISPAN is increasing their additional requirements to handle fixed networks from a common IMS core network.

MSO’s realize that their survival in this current climate depends mostly on their ability to compete with Wireline, Cellular and Voice over Broadband (VOBB) operators, offering converged voice, video and data services over IP to their subscribers along with the acquisition of new subscribers, offering them mobility (quadruple play). Existing PacketCable standards enable the delivery of high quality voice services over the broadband IP HFC network, however rely heavily on TGCP and NCS control protocols, both being Cable-specific variants of MGCP. IMS with its SIP architecture will enable video over IP communications, presence services, Instant Messaging, Multimedia services and mobility (handoff between VoIPoWiFi to GSM/CDMA). IMS is the architecture that will help MSO’s achieve the above goals, expand their subscriber base, increase ARPU and secure their competitive status.

Existing PacketCable 1.0/1.5 standards enable the delivery of high quality voice services over the broadband IP HFC network, and rely heavily on TGCP and NCS control protocols, both are Cable-specific variants of MGCP. PacketCable 2.0 takes the Cable industry to the IMS era, specifying an IMS-based architecture with end-to-end SIP control. Currently, as MSO’s deploy voice over IP services with PacketCable 1.0/1.5, it is important that the selected infrastructure (eMTA’s, Softswitches, Media Gateways, etc.) can be upgraded with minimal investment (optimally with updated software only) to support the PacketCable 2.0 standard. Support of wireline and wireless vocoders in the same gateway is also critical for being able to offer mobility services in the future.

MSO’s that own existing legacy TDM switches can take advantage of the excess capacity increasing ARPU and customers’ stickiness by offering VoIP services using V5.2 (or GR.303) gateways. At this point it is important to ensure that the same gateways can be utilized as Trunking Gateways in the IMS architecture at a later date.


There are still a number of issues facing IMS.

Stabilization of Standards: SIP is an evolving standard, making interoperability a challenging task. In addition, each new access type is bringing along a whole set of standard activities that impact the core network. Access agnostic is the goal, but not yet the reality. Each access presents a different set of challenges and requirements. It will take some time but as per early VoIP days, standards will eventually reach their equilibrium.

A mature IMS offering from Tier 1 Vendors and System Integrators: Many Tier 1's have to deal with existing products and solutions developed internally over the years. A large investment and time is required to alter the direction of big organizations, along with making them realize that development cannot only remain internal.

Competitive Applications: Everybody is looking for a unique application to justify their large investment in IMS deployments. This approach does not offer a new Application that can initially bring in a substantial amount of money. Many applications should be trialed first in order to establish their reliability. Voice is still the leader, generating a significant portion of the revenue. Video could play a definite roll in the future.

IMS is fast approaching as standards are being created and worked upon. Tests, trials, limited and mass deployments are time consuming, however the arrival of IMS is imminent.

AudioCodes is positioned to offer IMS, by means of a comprehensive set of media gateways, access gateways and media servers to fit into any IMS-compliant network. Since the inception of VoIP, AudioCodes’ media gateways have been working in distributed networks, which have recently been adopted by IMS. In addition, our field proven, IMS-compliant H.248 control protocol supports the necessary functions for IMS deployment. AudioCodes products already have a choice of multiple vocoders (like GSM-EFR, AMR, EVRC, iLBC, G.729A, etc.) necessary for building a truly converged core network for supporting GSM, UMTS, CDMA, cable and wireline access networks to enable interoperability with an IMS core network.

Finally, in addition to standards (or multi-standards) compliance, AudioCodes has teamed up with NEPs, System Integrators and Service Providers, offering best-of-breed media gateways and media servers with a full commitment to open interfaces and interoperability with 3rd party network elements, which is at the heart of IMS philosophy.

Our media gateways and media servers are available with SIP call control for use in enterprise and media server opportunities. We are closely following the 3GPP SIP standardization and assure IMS compliance with no hardware changes, thereby protecting infrastructure investment.