I have received numerous calls from this and other numbers supposedly from a company called Recovery Management Services or RMS.  Their employees often call leaving messages saying they are calling about "Client Number 404287278" asking me to call back at 877-567-2620.  The names are always garbled and I have no idea who that "client" is when identified only by number.   I have called back numerous times and no human ever answers.  If this is a collector for Sprint, I have no account with Sprint and they have my two-week old Verizon "Go Phone" residential telephone number that is unlisted and that has been given to no one.  They are calling multiple times per day and when I personally answer, no one is ever there. I'm losing my sense of humor.