accessibility without being able to touch iPhone or iPad at all

Hello everyone. My aging, severely disabled and technophobic mom often cannot use her arms or hands at all. We are looking for ways to make her communications via telephone, FaceTime, email, as well as possibly accessing music/tv etc. to be TRULY hands free. Has anyone successfully used accessibility features on their device to, for example, answer a phone call with Siri? (We all can initiate a call with Siri, but not answer one without touching, tapping or otherwise move a finger).