We have an AT&T telephone answering machine. We get tons of robo calls and typically let the answering machine handle them. The unit accepts the call and then the machine prompts for a message and then hangs up. Lately we are getting calls which terminate with our phone acting like it has been left off the hook. It starts beeping and the only way to silence it and ready the machine for use is to press the answer button and then the hang up button. Is there some way to prevent this?