Shows up as unavailable on my phone

I am starting to get calls from this number everyday and it says that its a collect call from "     "  and they don't say a name or anything.OF course i don't accept but its getting to be this everyday thing. How do we make these stop?

Got three missed calls from this number from Ohio, tried to call back to see who it was and was busy.

These calls are coming from the Northeast Correctional Facility in Youngstown, OH.  It's a federal prison, do you know someone who may be there?  Be Careful though, my friend tells me that inmates steal each others phone numbers and addresses, pretend they are that person and try and get money...

I know for a fact these calls are coming from the Northeast Correctional Facility in Youngstown, OH.  It's a prison that only houses federal inmates.  Someone you know may be trying to get ahold of you or be careful because inmates steal each others personal info and it may be someone trying to get money.  I guess the only way to make these stop is blocking the number.  My ex-boyfriend calls me from there and usually this is the # that shows up.