With the increasing expectations of mobile device users, GSMA has initiated Rich Communication Suite, a collaborative effort with leading mobile operators to enhance the deployment of IP Multimedia Subsystem services and bring it to the mass market. RCS provides a inter-operable and convergent communication suite to explore and enrich IMS multimedia services. This thesis provides an extensive overview of IMS and RCS architectures, messaging and transport protocols and usage of Session Initiation Protocol as rendezvous signaling. It describes how RCS uses IMS networks and enriches the IMS services and communications. Although all releases of RCS included file transfer as one of its communication services, those did not address issues associated with file transfer to multiple end users. This thesis describes elaborately how one-to-one file transfer can be done, how it can be expanded to multiple users and pros and cons of different mechanisms. It also shows the usage of RCS to enrich file transfer mechanisms. The tests in the scope of this thesis were executed using devices with various network and CPU capabilities. Finally, potential future works have been discussed. In the examples, all real world identities (domain name, URIs, server name etc.) have been replaced by mock identities.
