Received 3-4 calls/days for the past two days. No message is ever left and when I attempted to call it today, it rang for a solid 60 seconds and went to a "cannot complete this call" message.
If you are receiving the call on your cell and your carrier is Verizon, you can access your account on-line and block this number. If nothing else, you're phone will stop ringing at untimely hours.