The race towards mobility results in the emergence of different architectures and networks. The rise of Internet has given birth to the new architectural framework for delivering Internet Protocol (IP) Multimedia services, named IMS (IP Multimedia Core Network Subsystem). Those new internet-based rich real-time communications services need to be charged properly by telecom operators.

The real challenge is to adopt appropriate billing capacities while identifying the right address to charge the user account in IMS networks.

To solve successfully this problem, Ouroboros experts have designed a SIP-based IMS Gateway function (IMS-GWF for short). Session Initiation Protocol (SIP) is a key protocol which manages sessions on IP networks. The IMS-GWF acts as a SIP-application server which communicates with the Online Charging System (OCS, the core element that provides credit control for prepaid users) to get all the information on services granted to the subscriber and to monitor their usage.

The IMS-GWF can also communicate with the OFCS (Off Line Charging System) for the postpaid users. In this way, each communication service (Voice on Lte, Wi-Fi calling, enriched messaging or video calling) is correctly billed.

Ouroboros IMS-GWF provides a common IP interface that enables subscribers to use different applications to activate sessions through multiple mobile and fixed devices.

For telecommunication operators, those IMS centralized services simplify significantly the billing capabilities : less network elements reduce their operating costs.