simple SIP dialer for symbian mobile phones

I require a VERY simple SIP client for Symbian OS. Here is the list of the basic requirements: 1) SIP Server IP/domain needs to be hardcoded. 2) SIP Dialer should work in most editions of Nokia phones like N Series, E Series and 5th editions like Nokia 5800 Xpressmusic....... 3) Show Balance (Get balance from a url ... url will be provided)....[Optional] 4) a minor change to make it working through my proxy server .. (I will explain you during conversation.. ) 5) Dialer should work through GPRS, 3G, Wifi , Edge .. etc IMPORTANT: ----------------- Make sure your experience is related to this field. I know alot of developers have some ready made work to show and ready made code to sell which will be a plus point.......You MUST be familiar with the source code to answer my questions about source code and sip stack which you have used in the dialer.