Who called from 5084751336

Our company gets a call from this number at least two or three times a day.  Nobody is there when the phone is answered.  No idea who or what this is.

how do you block this or make it stop?

Three or 4 calls to y cell phone saying I had signed up for a 40 dollar visa card gift, or had signed up for instant cash online. I didn't and I don't know where they got the number... it started after I voted on x-factor through my phone and i wonder if it got sold that way. When I call this 508 number it says this number is not in service - how can that be?

Whoever this is asks for someone who is not at my number. When I tell them its a wrong number they hang up without an apology then I get another call 5 minutes later

Keep getting calls from this number, leaves no message and cannot call back - how do I stop this.