I have decided to take a mini vacation next week to San Fransisco and curious on some data plans for my iPhone. I have an unlocked 4s, so finding a Carrier shouldn't be a problem. I'll be there fr 6 days and will need data only, but small amount of voice minutes would be nice too, but not required as I have VOIP app on my iPhone. what sort of rates am I looking at, and which carrier? I think I would like to have at least 1gb of data. After some searching it seems tmobile would be the best option even though they only offer edge (for iPhone). How is the signal strength in Sanfransisco, and is edge REALLY slow? ( I have only used 3G). Would edge network be enough to make a VoIP call?