The wired line network has been well studied and widely used for a long time. Most of its protocols are so successful that passed the test of time. There are many similar tasks in mobile and wired line environment, and we would like to achieve compatible, inter-working solutions. So it is a plausible idea to use the protocols of the wired line network in mobile environment too. However, the mobile and wired line environment differ significantly; mainly the bandwidth is different in the two networks. Although the difference is going to be smaller with help of new generation of mobile networks, it will still remain significant. An acceptable solution is to compress these protocols. This article presents our research and results about Session Initiation Protocol (SIP) compression.

First we describe an implementation of SigComp layer, a solution for compressing messages generated by application protocols such as SIP. We have created a demonstration system, which connects two SIP user agents to each other and ensures the compression and decompression of the messages between them. After that we show our development about adapting various compressing algorithms for SIP compression, and we evaluate them.