This paper describes the architecture, design patterns, and implementation of a Unified Communications Solution (UCS) over a home grown thin implementation of IP Multimedia Subsystem (IMS). This thin-IMS implementation makes use of IMS core components, and can serve as a first step towards migration to full IMS. The unified communications solution offers a rich set of services including duplex VoIP, video conferencing, instant messaging, media sharing, child position tracking, active contacts, and email reading. Subscriber profile is leveraged by a targeted video advertisement preview service as a payment method for calls terminating at landline or mobile networks. Subscribers can also use prepaid service for calls terminating outside of the IP networks. In addition to system and software design patterns, the paper addresses critical deployment issues, such as scalability, NAT traversal, network interconnect, ease of service provisioning and administration, and last but not least, user experience. Finally, the paper contrasts the thin-IMS platform to 3GPP standard IMS release 7 specifications.
The CASPER user-centric approach for advanced service provisioning in mobile networks