I got the same thing - an immediate hang-up when I answered.  I've ingnored their previous calls because it's an unknown number to me. They call my cell phone.  Today I finally decided to see who it is, and they hung up.  When I called the number back from a different phone, a lady answered "GM Credit" - I don't have or need GM Credit!!  I would like to know who or what this is.

They keep calling me and not leaving a message. I have no debts so this is stupid and I don not know anyone named "Michael Ragland". Glad I checked this number out before I answered.

gmc credit services, not to be confused with GMAC, the credit arm of general motors.
this is just another fly by night  operation trying to collect old written-off debts

call them back for free at 1-877-315-0489

tell them you will hit redial and call them a dozen times for every time they call you.  
tell them not to call your number any more.
you do not have to give your number, they have caller id and know from what number you are calling.
ask them for the name and address of their attorney of record, so you can include it in your complaint to the texas attorney general fraud division

again free 1-877-315-0489

Glass Mountain Capital aka GMC Credit Services... an aggressive collector of old debts

got a call from the same company... apparently a debt from whoever previously had my cell no.