To send SMS, you just need to include the +country code before the mobile number. And make sure to inform the recipients that it's you and that they reply on your mobile number and not on the US number. I'm not sure on how much the telcos will charge them if they reply to that number.
Anyway, before sending a SMS, better check the list of providers in the country your going to send. For the Philippines, you can send SMS to Globe, Smart and Sun subscribers.
Let your friends know about this free SMS worldwide using your iPhone.
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