Called at 8:30am.  Caller ID showed "I".  Didn't leave a message.

Called at 7pm on a Sunday. When I answered they just hung up.

Called at 8:27PM on a Sunday night. Rang four times before giving up.

I have received the same caller several times sometimes male sometimes female

Received yet another phone call from the same guy who listens to the voicemail message, but then says, "Is Jason there? Hello? Are you there??"  This is the seventh call I have received from this guy, and it's not only this number he is calling from. I have reported him each time and with each number he calls from. The caller ID only shows "I".