I received a text saying, "Hola Douglas??" I replied, "Hola? Quien esta?" and got no response after that. My guess is that I confirmed that it was a valid phone number.
I just got a text from this number, too. Considering I don't give my cell phone number out to just anyone, it kind of annoyed me that some random number texts me saying "hola jillian???"
It seems all these comments are pretty recent, I too got a text saying hello and using my name as well. I agree that it's probably a computer program verifying cell phone numbers to spam-text people that respond which confirms the number for them. Best thing is to not respond.
http://www.andersoncooper.com/2012/05/16/bewa ... ity-theft-scam/
Tighten up the security on your accounts and don't click unknown links. If they've told you their Yahoo ID, report it to Yahoo abuse.