Multiple calls from this number with no response from caller when phone is answered

This person has called me more than 50 times in the last month, leaving me about 20 voicemails. All of the voicemails are of heavy breathing with background noise. They call constantly, often late at night.

I've been getting calls from this # for quit sometime now. The phone has been off and down in a bag for months, I take it to use as a spare and the calls have been coming since I turned on the phone on the 7/21/13.