I keep getting this phone number on my cell phone and it is NOT wanted. How do I get them to stop calling me??!!

I just received a call from this number, too. I don't think I know who it is. It did leave a voice message but I haven't listened to it. I'm assuming it is spam phone call. This number called me on my private cell number.

I do not know who this is and they keep  calling with a recording that plays.