The Datagram Congestion Control Protocol (DCCP) is a new Internet transport protocol. It is meant to serve as an alternative protocol for applications that require low delays and where a certain degree of data loss is acceptable. TCP is not well-suited for these applications, since its reliable in-order delivery, combined with its congestion control, can cause arbitrarily long delays. UDP avoids long delays, but UDP does not provide congestion control. DCCP provides built-in congestion control for unreliable datagram flows. DCCP supports several different congestion control profiles. One such profile is aimed towards small clients, i.e. devices that have limited memory and/or processing power. An example of such a device is the mobile phone. Modern mobile phones today use the Symbian OS, which is the standard operating system for mobile devices. The goal of this Master Thesis was to implement DCCP with the thin congestion control profile in the Symbian OS. Experiments show that the DCCP implementation adapts well to changes in the network and in the mobile phone, but that the currently available communication technology, GPRS, is too limited to support real-time applications where DCCP could be applicable.