Don't know what they do, exactly, but it's odd to me!  I signed up online.  They ask for a credit card, and they insist that it not be an ATM card with a Visa/MC logo.  I used my ATM card anyway!  After going through a divorce, I know my credit is wrecked.  So what do they do?

Nothing.  No deposit, no crazy charges, no denial of service.  Three emails and two phone calls welcoming me to UVerse and reminding me of my install date and time.

There is no way I shouldn't have been charged a deposit.  But I haven't been.