Hi, and welcome to Just Answer.
That phone number is XXXXX in published listings, probably because it is a fax number. The only way to find out who your faxed reached, is to pay for a 'report' on the number from a company like 'Intelius'.http://www.intelius.com/results.php?ReportType=33&searchform=phone&qp=[866-724-4255]
However, this type of error happens quite often, and usually it's just best to leave it alone. If they don't know you and have no idea why you are sending the fax, they will just dispose of it and forget it. But, if the information was personal and/or might enable someone to steal your identity, for example, it would be worth it to find out who received it or make any changes you can, to the information you sent by accident, so you are protected.
Your local phone company might also be of help in identifying this number, after you explain the circumstances.
I wish you much good luck!
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