This number will call you and leave multiple voicemails. I have traced the number back to Verizon Business DBA MCI WorldCom. Neither MCI, Verison Business, or Verizon Wireless want to do anything about it.
The number works until they block you via caller ID. They do not accept private or blocked number calls.
2815028176
They are registered within the 281-502-8xxx phone number block.