Just got one in reply to a craigslist.org posting as well. Google is your best friend. Found this after receiving the same message. Likely a bot for roomester,com. GD scammers.
Number came from a Chicago area code. I mentioned Chicago in my email. This may be where they pull their reply number from.
Number in text reads: 202-524-2429
" Room still open. pls sign up here http://jessica.roommatenext.com & lemme know for da next step. Just prove u r not marketer/robot"
Like I'm going to "prove" anything to any unknown person by hitting that link.
A simple phone call to my cell phone would pretty much be proof enough if THEY were REAL!