Third generation wireless systems are expected to provide wide-area wireless Internet and multimedia services including multiparty conferencing based on the Session Initiation Protocol (SIP). Satellite UNITS (S-UMTS) constitutes a promising alternative for the provision of these types of multiparty conferencing services due to its wide area coverage properties. However, supporting multiparty conferencing over S-UMTS is a challenging task due to the more complicated signalling involved compared to point-to-point sessions, and also due to the more adverse channel condition and long round trip delay encountered over the satellite radio links. This paper describes the end-to-end signalling flow for conferencing creation over S-UMTS and investigates its performance over the satellite radio interface. The variations of the Radio Link Control (RLC) parameters and retransmission options on the overall conference creation performance are also examined.