The way understand it at hacktheiphone.com, I can use my current SIM from AT&T if I jailbreak it. Assuming I have a voice and unlimited data plan, what will I be losing by using my current SIM card instead of using the one provided with the iPhone? It seems I will mostly just lose out on Visual Voicemail. If that's the case, I'm ok with it. Also, should my unlimited data plan work the the iPhone? Thanks!