I have a Samsung Captivate from ATT with stock Froyo (Android 2.2). I am using a T-Mobile prepay Sim Card with the phone (no 3G/data plan). I have rooted and unlocked the phone, and initially (for several days) the phone worked perfectly without problems. I took a trip from the US to Vancouver, and while in Vancouver, I texted back and forth a few times to the US and made one phone call (Rogers Network) without problems, using data roaming. When I returned to the US, my problem began. I can still text without problems, but when I make a phone call, my reception consists of mostly or all static through the earpiece, speakerphone or earphones. The person on the other end can hear me perfectly, but I receive static. I also receive static when I dial up voice mail. My earpiece and earphones work OK with music and voice recordings. There have been a couple of occasions where the static went away and I do not know the reasons for this (the static later returned). Other than the static, I have no other apparent problems with the phone. I have tried a factory reset and that did not correct the problem. I also installed the simcard from my husband's iphone, and the problem was the same (static on reception). I was wondering what else I could try to correct the problem: 1) Should I reinstall Froyo or some other ROM? How would I do that with a rooted and unlocked phone? 2) Could it be a modem problem? How can I check and fix this?