I have an iphone 4 in australia. plan is to unlock it before i go and use it in north america. firstly, does it have the correct frequency and will it work?? and secondly, is it easy to purchase pre paid sims in america for phone calls and data??
Will my iPhone 4 work in North America??
oh, and do the location services on the iphone work the same in north america?? will i be able to use the gps capabilities of the phone?
Your iPhone should work just fine in the US, as they are meant to work in most countries (the days of phone not being tri-band are mostly behind us I think)... I imagine getting a prepaid sim is as easy in the US as most of the rest of the world. You can also get one before you leave home (we work with Telestial), but I'm not sure how it ends up comparing in the long run to other options inside the US. If you don't mind waiting till you get there to get your new phone number, I'd probably just wait and sort it on the ground.
Your iPhone should work fine here as long as you are on one of our major networks (Verizon, AT&T, Mobile 1, etc.).
One thing I would check on is whether they will charge you roaming rates (I think not, but better to check). Also, some phones require that overseas options be unlocked before leaving your home country. Lastly, check to see what the charges are for data plans for overseas travel (including texting), since these may be another giant charge they will tack on.
As indicated above, prepaid calling cards are very cheap and easily available either in your home country--or at essentially any convenience store (for example a liquor or drug store) in the US or Canada.