what to do with such chatterboxes?

I tell my kids they talk too much. Zip it. I used to work with people I had to drive around and one of them never stopped talking about the most inane things and then she would start repeating it all. I would tell her she really had to be quiet so I could concentrate because the traffic/weather/glare/whatever was really bad and I needed quiet. I have a relative that does this as well and when I am visiting any other relative and she calls I get told to call on my cell, which triggers call waiting, and then they are able to get off the phone by saying they have some other important call they must take. It's very sad. Can' they get a hint without all the subterfuge?!