please could any one tell me the cheapest way to call England, from a mobil phone while staying in USA

Is this a mobile phone that can dial free local phone numbers in the USA, or can dial 800tollfree calls at no charge?

I have friends visiting USA taking their mobil phone with them ,they will have to phone England ,should they buy a sim card in the USA ,if so which card & where to buy a card from ?

Can they ask their UK phone carrier or email the phone manufacturer? Might be best way to get reliable info.

If their phones are unlocked and work on US frequencies, then they can buy sim cards at Cingular, T-Mobile or other GSM providers for pay-as-you-go. If their phones aren't unlocked, they might be better off buying PAYG phones here rather than paying humongous roaming charges on their UK account.

There are a gazillion companies that offer inexpensive international phone services. For example here's one (that we're using for international callback on our RTW trip starting in a couple of days), but many similar outfits. http://globaltel.biz/int/

While staying in the USA they probably shouldn't USE their mobile phone for calling UK. They should buy a calling card that they can use in their hotel, in a payphone, or at the home of their hosts. The calling cards require you to just dial a local number for access, or dial a toll free 800 number for access. My green CONNECT card costs me 3c per minute for calling UK as long as I am near a phone where i can make a free local call or 800 number call.