How do i send a text to my mate in the USA from the UK?

[Jenn]

Recently i made friends with a girl in the USA and were really good friends now. She's even the co-owner of my twitter account. We have exchanged numbers but neither of us are able to send a text message to the other.
She has mentioned something about a "Country code" and i have no idea what this is.

I would really appricate the help.
Thank you

[Link]

There is a whole new invention called emails and IMing.

[yelowvanman]

To call United States from UK you have to dial 00 + 1 + City Area Code + Number you wish to call.
To call UK from the USA dial 011 + 44 + phone number
This is the same for calls or text.