There's no law or rule of etiquette that says you have to drop what you're doing, interrupt a meal, lose your train of thought, or miss your favorite show…to answer the telephone. Unless you want to. If not, screen your calls with caller ID. Or let your voice mail pick it up. There are few things that can't wait until you're available to talk. And you certainly don't want to be waylaid by an endless yapper. Busy? Let the phone ring.
It's stupid to do things that you don't like to do, so why make yourself unhappy? No need to worry about these boring things, just let them go.