If this was from connect hearing then they ought to know some people couldn't hear the ring, and some people will not pay to return the call not knowing who they are calling. Yes, there are people who do not have phone plan and they pay for every call.

A large company like 'connect hearing' can certainly do the right thing, and ask their marketing department to do the ethical thing, and send a text message, especially when they are calling a mobile number. But no, they insist on acting like pests.