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Next-generation networks (NGNs) are set to offer ubiquitous converged services comprising voice, video, and data services irrespective of the access network. The IP Multimedia Subsystem (IMS) has emerged as one such unifying architecture that allows delivery of identical services to fixed and mobile customers - regardless of whether they are connected through a packet-switched (PS), circuit-switched (CS), wireless, or a cellular network (3GPP, 2007; Jin-Ho, 2010; Jun, 2006). IMS-based services enable communication in a variety of modes including voice, text, location, presence, messaging, pictures and video, or any combination of these (Saxtoft, 2008). IMS distributes functions over specialized network nodes allowing for scalability; that is, as the subscriber base grows, the IMS network can seamlessly scale up by adding extra nodes (Gateways). Thanks to the flexibility of the Session Initiation Protocol (SIP) and Session Description Protocol (SDP) used for signaling (3GPP, 2005), IMS can accommodate convergence, with the potential to meet all the needs of Unified Communications (IMS SIP, 2009). SIP's flexibility enables IMS networks to adapt and change signaling protocols to meet dynamic market needs for telecommunication services.
Yet, despite the high initial convergence expectations and the promises of revenue sharing for Telco offered by its open architecture (Cuevas, 2006), IMS has been slow in penetrating the telecommunications core network market (Finnie, 2007; iLocus, 2010). This is mainly because of the weakness of IMS business case in the face of complexities in rolling out fully compliant IMS solutions (http://www.openimscore.org/). It is our belief that service providers will/can settled for solutions that are diminished implementations of IMS standard architecture, that can still bring in the power of SIP signaling and core IMS components, that is P-CSCF and HSS nodes, without the complexities of the standard peripheral nodes such as BGs, SBCs, and I-CSCF nodes, perhaps as a first step towards the deployment of a fully compliant IMS core network.
This paper presents a complete solution for subscriber unified communications services (UCS) built on top of our home grown implementation of IMS core components dubbed thin-IMS. While thin-IMS platform uses only a subset of core IMS nodes, it retains high degree of compliance with IMS release-7 standard architecture (3GPP, 2007). The unified communications solution comprises subscriber client software for PC and mobile devices, a rich set of Application servers, and various other modules implemented at the level of the Gateways using proprietary protocols to ease deployment, administration, and client self-care.
From a business model point of view, UCS makes provisions for sponsored publicity spot viewing as a payment method for calls terminating outside of the IP network. This feature offers Telco the means to redirect part of the traffic (and revenue) on their core IP network currently used by VoIP applications such as Skype. In UCS calls can also be made to mobile phones and landlines using prepaid cards. As such UCS leverages the power of thin-IMS to provide the service operator with an extra stream of revenue from the publicity market, while offering a free alternative to making landline calls.
In addition to delivering targeted ads, the engineering of both thin-IMS and UCS took into consideration a number of key functional and non-functional requirements, namely: low cost of ownership, ease of roll out and administration of services, a rich user experience packaged in a single client console. The latter includes functionalities such as Active phonebook that extends presence to accessibility by voice, video, email or instant messaging channels; a tracking service, that delivers notifications as soon as a target (one’s children, for instance) exit a predefined tracking area (a school for instance).