Cell Phone application development

We are looking to develop an application that would run on a variety of cell phones. This application would keep track of the phone activity (date/time, duration, to/from tel number), as well as call recording. Call recording would be available either "always on" to record each in/out call, or "on-demand" (while on a call, you can punch in pre-defined keys to start recording). Additionally, there must be a way to upload this information to a server (design of this server is part of this project). We understand that development platforms will differ between phone manufacturers. We need a flexible solution that could be applied to most with a minimum modifications.