I was wondering if anyone can help me with my query. I have a mobile phone - Pay-as-you-go, on the Orange network and am to visit the States soon. Will I be able to I use it there?

The phone will have to be at least tri-band, if not quad-band since the USA use different frequency bands for GSM to those used in Europe.

You'll also find that GSM coverage is often restricted to larger towns and cities and major roads, generally along the East and West coasts, rural GSM reception is non-existant or patchy at best.

and almost the rest of the world.

if you intend to use a Non Orange SIM in the US you'd also need to get the phone unlocked...

Thank you one and all, for the info. I will consider buying a new phone.