To text the us if the person is on a us mobile network. You will need to place +1 in front of there mobile no.
If the mobile no begins with a 0 (Which i dont beleive us mobiles do) you would just remove the 0.
I sms the us all the time and dont have any problems.
It cost me 12p to send to a us mobile
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If the person you are texting to the us holds a uk number, then you do nothing. as the person has a uk mobile no, this never changes so its just like sms from the uk to the uk.
Hope the above helps
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