How do I find out what content types are support for my platform?

The Manager class has a getSupportedContentTypes() method. Passing in null will return all the supported content types across all protocols. Passing in a specific protocol will report the content types supported for that specific protocol only. Like audio/midi might not be capturable, but you could play it, on a specific device. Keep in mind that the set returned from the wireless toolkit is apt to be different than a real phone.