Just throwing this out there in case anybody wants it.
You can SMS an international number such as one from the UK to their UK number (+447xxx) using Google Voice, then once they reply you get a special Google Voice number(406-###-####) and once you get this you can SMS them as you would any number and it will relay through google voice at no cost to you!
Caveat: Calling this 406 number *WILL* cost you at the Google Voice rate for calling the UK (or whatever country you are SMS'ing to).
Happy texting!
