805-637-7243

Well said.  There is a T-mobile Community page questioning the identity of this number as well but it is 4 years old. No one from T-mobile responded to clarify.  T-mobile seems terribly silent on the subject. Call back gets, "You've reached the voicemail system.  If you have a mailbox on this system, press star.  Please enter your 10 digit phone number. I entered a random string and got, "Sorry that number is invalid."  It does seem to be a voicemail system but as you've pointed out reports are confusing and some spoofing may be at play.