Based on several websites that seems to be the number of a collection agency called NCO Financial Services. According to NCO Group to Pay Largest FCRA Civil Penalty to Date they were in trouble with the FTC back in 2004 and based on Expert Global Solutions, Inc., as NCO Group, Inc. they got into trouble again and got hit with an even larger fine in 2013.
Somebody mentioned that connecting a fax machine to the phone and have it turned to the max volume helped to get rid of them. Isn't a machine rather than human calling?