The third generation (3G) of mobile network systems is seen as the technology that will bring the full scope of Internet services to the cellular world. In order to fulfill such ambitious goals, 3G specifications have been evolved into cellular networks with full capabilities of understanding the Internet protocols. The two major protocols proposed, Session Initiation Protocol (SIP) and Session Description Protocol (SDP), are the driving forces of such a merger. They are capable of initiating, modifying and terminating multimedia sessions currently available on the Internet. This project investigates the performances of the multimedia session setup scheme, based on SIP and SDP, over Universal Mobile Telecommunications System (UMTS). Particular attention was paid on the wireless portion of the UMTS, and we developed SIP layer virtual link, namely User Equipment (UE) to Proxy-Call State Control Function (P-CSCF) link. The link model used in this project reflects all the lower layer mechanisms specified in the UMTS air interface such as channel codings and interleaving schemes. A major concern with SIP in 3G networks is to ensure the efficient use of the bandwidth constraints inherent in the wireless medium. Because of the significant size of the SIP messages, 3G terminals can suffer from substantial set-up delays. We investigated the implication of using the compression scheme of SIP messages proposed by Internet Engineering Task Force (IETF), called SigComp. The evaluation was carried out to obtain the savings in terms of delay and multimedia session initiation attempt failures. A novel scheme that can replace the plain text based application protocols for increasing time savings and reducing the load of the SigComp layer is also proposed. The scheme, referred to as Binary Hybrid paradigm of protocol design, is based on binary sequences and plain texts. This paper evaluates the performance of this scheme with contrast to the normal SigComp/SIP. The major focuses of the investigation are how much time delay the schemes are likely to cause and how many session attempt failures are likely to occur over the UMTS wireless link at the given channel conditions.