In the past few years the sales and market share of smartphones capable of running multiple user installed applications have been showing a constantly growing tendency. In the meantime the spreading and improving 3rd and 4th generation mobile systems are being used by more and more people for not only traditional telecommunication services, but also for a wide range of IP based services. These two factors combined present a good opportunity for creating new services that can take advantage of the user’s constant online presence.
However the mobile devices’ very limited resources, the diversity, and the commonly present restrictions of the communication infrastructure available make the efficient implementation of these new services a rather difficult task. This paper first introduces these challanges and highlights their possible solutions, then it describes the design and implementation process of a system that provides communication services for SIP (Session Initiation Protocol) based and web services. This system can be used for implementing client applications built for mobile devices that can be easily integrated into existing SIP or web service architectures without requiring any changes of those, while it manages the network communication of these client applications in a way that utilizes the resources available for mobile devices as efficiently as possible.