Provision of caller ring back tones for IP multimedia platforms

Abstract

Customised Caller Ring Back Tones (CRBT) are used to entertain callers by playing a media clip while the callee’s phone is ringing. CRBT involves the mobile operator replacing the standard audio clip with a clip selected by the user, in this case the callee. The service may be offered by 3rd party application providers, but can also be offered by mobile operators themselves. CRBT service can be supported by different mobile network infrastructures including the circuit switched GSM networks and IP multimedia networks such as IMS. These networks need integration of additional components to provide the CRBT service.3GGP has standardized the IMS architecture, which comprises transport, control and application planes. SIP interface to application can enable 3rd party application providers to offer value added services such as IPTV and CRBT. RTP packets conveying media for these applications would be streamed across transport plane connections. This paper presents the design and implementation of CRBT on IMS networks. It presents considerations for deploying both CRBT and reverse CRBT. The design adopts the architecture where an IMS application server is used to control CRBT service, while the media is stored and served from an RTSP media server. We utilize the Fraunhofer Fokus open source IMS core and UCT IMS client for implementation. Test results are geared to proof of concept; performance tests show minimal added call setup delay of 15 millisecond.