Android- put a call on hold and add new call

I would like to write an app that will put the current call on hold, then add a new call. Since this can be done by manually pressing buttons, I would think there is a way t开发者_StackOverflowo do it programmatically, but I cannot find anything in the sdk.

TIA

Since the Phone.apk can't compile directly from the android SDK because it uses objects and methods that are not publicly available in the SDK, you would probably have to build an app as part of the "platform" so you can have access to the same objects and methods that an app like Phone.apk does.