I missed a call from this number and no message was left.  I blocked my number and called back.  It rang about 4 times and a woman answered by saying something unintelligible, then "Hello?.  She put the call on hold or mute or something and picked up again in about 15 seconds and said the same thing.  Heard boiler room noises in the background.  Did the same thing over about 6 times until I got bored and hung up.