Does anyone know if a tourist in US can buy a pay as you go phone? Does the person need a fixed US address? Or even just buy a pay as you go SIM card for GSM phone. Is that available in US? I know some other country provide that service.
You don't need an address. You can walk into a store and pay cash. Beware that unlike e.g. Europe, in the USA you pay for incoming calls as well as outgoing ones! Or you can get a USA SIM card. All you need to do is ensure that you have an unlocked Tri-Band mobile handset and then simply switch your home country SIM card for your new USA SIM card on arrival. This UK firm sells them for £19.99 for Jolt Mobile http://www.0044.co.uk/america.htm