This number called my home phone last night at 9:30, and this morning at 10:00.  They said nothing last night after I said "hello", so I hung up.  This morning, they also said nothing, so I put the phone on Mute to listen.  There was definitely someone on the line (you could hear rustling, breathing, other movements periodically), but they never said a word.  I left the line open, listening to the muted handset for nearly 10 minutes before I hung up.