It's fairly common knowledge that when using the Droid Pro or another VZW global phone at home in the states, one should set the phone to CDMA mode to preserve battery life. I've always done so with my pro, but every once in a while I would notice my battery draining faster than usual and discover that the phone had switched itself back to Global mode. So, a couple days ago I decided to see what would happen if I just took out the SIM card altogether. When you remove the SIM, the phone stays in CDMA mode (in fact, it won't even let you manually switch to Global) and normal functionality is not impaired. I could be imagining it, but my battery life also seems noticeably better. My thought is that that with the SIM card removed, the phone is unable to even look for GSM networks. Just make sure you put the SIM in a safe place in case you ever travel. Hope this helps someone!