Auto-Roam?

[arparent]

I just noticed while taking a call, that when I am roaming at my parent's house, I get a MUCH better signal then on the home network. However, everywhere else, I get a better signal on home. Is there any way to get the phone to determine which gives a better signal, and go with it automatically? I don't really like the idea of manually changing it, because I am very forgetful. Just curious, I'd like to be able to receive calls at my parent's house.