It is illegal -  it is unlawful for any person to make any call (other than a call made for emergency purposes or made with express prior consent) using any automatic telephone dialing system or any artificial or prerecorded voice message to wireless numbers. This law applies regardless of whether the number is listed on the national Do-Not-Call list.

File an online complaint to the FCC on their website regarding this number. Also file a complaint on the FTC website and LIST this number.
Eventually enough complaints will get action. There are millions of us being harassed, and a few of them...overwhelm by numbers!