Imagine you are developing a "free" app for android & iphone and want to refinance yourself through using some sketchy ad service. Does an app delveloper have to worry that the ad content he embeds can access information such as the user's phone number or maybe even his phonebook. Furthermore, is there a some danger that the user's phone number can be made public if the clicks on the ad?
Naivly I would image that all this information is safe on both android and iphone. Hearing from many stolen phonenumbers I was however wondering on what technical ground the access to such private information is "granted"?
I'm happy about general answers or more specific answers just covering one device type.