Forgive me if this isn't the right forum, but it's tangentially related to the iPhone. I have Cingular/ATT, and the signal in my house is horrid. I usually can't place a call, and when I do, it gets dropped. My dad has Verizon and gets great service, but also a different phone model. I want to put my SIM card in his phone to see if I get better signal (to see if it's the service or the phone that's the problem) to see if I could even use my iPhone if I got one. Will putting my SIM card in a different make/model phone sold for use on a different network mess anything up? Or will things go smoothly? I just don't want to ruin his phone (or mine). Using my SIM card in his phone will make it use the ATT network, correct?