855-707-9380

I was charged because I returned a call to this number 9.99

You weren't charged because you called  a  1-855 number.  Tolls for 855 numbers are billed only to the owner of the number.   Someone pulled a fast one and just  billed you through your phone company for a service or something.  You can contest that with your phone company and probably get it take off your bill.

Neither of the posts above are necessarily completely true or completely false.  If a person has limited airtime on a cell phone network, it can cost (using my cell phone as an example) $ 0.45/min for airtime in excess of those minutes -- and it is all billed by rounding up to the nearest whole minute from the second that I send the request out over the cell phone network.  This is completely separate from any cost for calling the number itself.  Thus, if I call a toll-free number for over 22 minutes and I start the call just after I use up my allocated minute for the month, I would get billed $10.35 for the call -- even though it was toll free.  And that's a phone company charge that would probably NOT be taken off the bill by request to the phone company.

The same holds for calls to toll-free numbers over VoIP networks.  Some of these networks (not all) charge a nominal fee for calling a toll-free number or even the regular rate for any regular non-toll-free number in the U.S.  Typically, such charges are only $0.02/min or less, and some companies charge only half that for toll-free calls (or even nothing at all).  So it is possible to be charged for calling a 1-855 number this way, too, but probably nowhere close to $9.99.

But, everyone should know that 855 numbers are treated no differently than 800 numbers and should not result in any charge to the caller in most cases, provided the caller is in the U.S. or Canada.  If you were charged other than for air time over a cell phone network or for minutes of dial-out time in excess of a nominal fee for calling over a VoIP network and you did not consent ahead of time to such billing, and yet your phone company is trying to collect this charge, contact your phone company and contest the bill.

Remember, though, that when you call back ANY toll free number (not just 855 numbers), you CANNOT keep the number of your phone private.  All toll free numbers (800, 888, 877, 866, 855, and eventually 844) give the calling number to the owner of the toll free number because they get billed according to the rate center from which you are calling.  And that's part of your own phone number.  If they did not get this detailed billing, they could not reconcile their phone bills.