Simple Yet Advanced CELL PHONE APP

Seeking App Programmer who has in-depth knowledge of accessing cell phone features and understanding of their limitations. Please do not respond if you just have app development experience, but not in-depth knowledge with Android, Apple, and phone carrier limitations.

I am looking to develop an app, but one technical phone feature, never tried before, must be able to function. If you are highly skilled with cell phone technology, contact me for more details on the project.