I had the same problem. Received the bill from AT&T last night, unusually high, and found the USBI charges on the back. We matched it up with the month prior and found it there again. I called AT&T today and conferred with a supervisor for a half hour, getting a lot of information.
This practice is referred to as "slamming" by the phone co. These third party companies like Cheap2Dial, steal your personal information online and add it onto your phone bill. In some cases, they have the capability to actually alter your service, replacing your normal long distance carrier with theirs. What they are doing is illegal according to the FCC.
I spoke with someone at Cheap2Dial to dispute the charges, and they told me that an "online enrollment form" had been completed and all they could do for me was to cancel the service. The second I demanded reimbursement of the charges, she hung up on me.
We need to be diligent in reading our bills and doing whatever we can to protect ourselves from this kind of fraudulent activity. The phone company has a 3rd party verifier department where you can set up safety measures.