How can you call an american cell phone from an English landline?

I am trying to call an american cell phone number, from my landline number In England, Nothing I try is getting through. I believe that there may need a + at the start of the number, however I cannot find a + on my landline phone. Can anyone help please? Thanks.

You don't have to add a plus sign. Instead use 00 (these 2 digits can be replaced by a plus sign when calling from a cell phone). So you will dial the following: 00 + 1 + 3 digit area code + 7 digit US number. If this still doesn't work there is a problem with the line you are using - it may not allow int. calling.

Note that in the US cell numbers are not differentiated from landlines. Here's a website providing US area codes: http://www.areacodelocations.info