what is the code to send a message to a cellphone from mexico to united states?

Answer 1

just send the message to +1 area code phone number
like so:
[phone]

You can get the + by holding down the button on your phone that has the + sign on it, usually 0 or *, sometimes you have to just hit it twice in a row fast.

Answer 2

When you write a message , in the space where it says to put the number of the person . It's normaly (recipent or TO)

Put +1(this is the code to usa) >>>>> Then the city code for example New York so it would be 718 and then the number and then send.

+1718XXXXXXX

i hope it helped