Examining my mobile phone bill today, I saw a suspicious charge called "Ask Mozoot Alerts" under the Mobile Purchases & Downloads: Communication Charges section.
Somehow I was signed up for (I use passive voice because I do not recall or know if this was there was an action on my part that precipitated this) a text messaging service called MoZoot. Users text them questions and they answer them; not terribly useful considering I have Google and the full internet available on my phone. Worse still, I never remember
(or at worst never actually did sign up for it) signing up for this service. Unsolicited text messages aside, this service insidiously adds a $9.99 recurring montly charge to your mobile phone bill, until you opt out.
As far as I can tell, the vector of infection (I consider this despicable company not so much a service, but more malware/virus upon my mobile phone) was an unsolicited text message that I merely opened. Granted this could just be a symptom, meaning they got my number elsewhere and just texted to inform me that my phone has now been infected with their "service." It seems you have to reply with a "stop" text message, otherwise the monthly billing persists, despite never actually using the "service." Such services should only be opt-in, not opt-out.
It took two months to realize this (thanks to auto-billing), but fortunately AT&T refunded both months of charges. I didn't lose any money, but what a hassle. There was little information about this online, so I thought I would do this service for others similarly afflicted.