I live in canada, and I have the virgin mobile plan, on my Samsung Gravity 3 phone. My friend lives in Washington, and when I text her, she gets it, but when she texts me, I don't.
I know its not an International/North American problem, because I text someone else who lives in the USA, and it works perfectly. I can their texts, they get mine.

But with my one friend, I cant get hers, but she gets mine. Could it be Virgin Mobile, or my phone? Or her phone, or her carrier?