RTP redirection using a handheld device with Minisip

Abstract: This report presents several different techniques for diverting RTP streams when using a handheld mobile device. This device is running a version of Minisip as the SIP user agent. An introduction to the SIP protocol is given to provide some background to the reader prior to focusing upon the main goal: redirecting RTP streams. A set of requirements are defined and an RTP media transfer mode is chosen based upon these requirements. The requirements are derived from a study of a Linux cellular phone’s mobile device features and capabilities. Minisip was ported to this platform and a series of tests conducted to evaluate the design decisions made. These tests show that the best method of redirecting RTP media streams is third party call control (3PCC).