I got the same "Test Message" on my cell phone that came through 10 minutes after I posted an ad on Craigslist. I'm sure that's where scammers are getting their phone numbers from. Text message said "Customer issue, credit union west service frozen please call 201 484 8652.
Just got off the phone with Sprint and told them to block all short codes. All sprint customers should call and complain as well request the short code block. Hopefully it works