What Is Proper Texting Etiquette When You Don’t Know Who’s Texting You? [POLL]

Today is my wife's birthday and she got a text from an unknown number saying 'Happy Birthday'. How do you respond with the hope of finding out who it is?

You know you've had those text's that get you wondering who in the world is texting you. It's from a phone number that's not saved in your phone, and they don't say "this is so-and-so", just assuming you know who it is. Obviously you're curious, and wonder if it's somebody you know or somebody you wouldn't want to have your number!

I always respond with "who is this?", coming straight out and asking. My wife feels that's too forward and not the best way to respond. She responds with "how have you been?", in hopes they will give a little information for her to put together who it is. I don't like to waste time trying to figure it out and get right to it, even if it comes off a little rash.