Is it possible to write a cellular phone telephony application that works with a current mobile carrier's phone software to handling INCOMING CALLS? Please answer this question first and explain why how that is possible.
If this is possible, I would like to have a custom develop SETTINGS APPLICATION that would reside on any SMART PHONE such as iPhone, Blackberry, Android, or iPad that would allow a user to either --
a. goto voicemail (required)
b. play a specific ringtone (optional)
based upon the CALLER ID.
Meaning, for certain phone numbers recognized by this application, the phone would go to voicemail directly rather than ringing the phone as usual.
For example, if I added 919-123-0909 to the list, anytime that number called, it would goto voicemail and not ring the phone.
Of course, the user could enable or disable phone numbers.