Okay, so you're starting to come down from your post-purchase iPhone 4 gadget high and you're getting into the habit of using it just like you would any other phone. FaceTime was a neat trick on day one, sure -- but if there's a single thing significantly limiting its day-to-day usefulness, it's the fact that you can only use it over WiFi at the moment. Apple claims that they've got more work to do with carriers to make it usable over cellular, but how legit is that claim?Seeing how MiFis and other mobile hotspot devices have quickly become a staple of doing business for us, we had a few lying around and figured we'd give it a shot: connect the phone to the MiFi, connect the MiFi to the 3G network, and give FaceTime a whirl. Our first attempt -- a call between Chris in the US with a Verizon MiFi and Richard in the UK -- failed pretty miserably (unlike our transatlantic Fring call ), but a second call entirely within the UK using a 3-branded MiFi from Huawei worked quite well, as did a US-to-US Verizon call between Chris and Ross. In other words, it's definitely possible, but you might not get as flawless of an experience as you'll get with a nice, fat landline data connection backing you up. Follow the break for all three videos.