There could be a simple reason, he might have run out of money in his account or minutes available in the month.  Most institutions have limits on the number of minutes an inmate can call in a month (not the by the calendar but by date it began). If you are really worried, you can call the institution and have them check on him to be sure.

There is no way of knowing who the caller is without getting the actual prison involved. The prison calling system tracks and records all calls. If you want to pursue it, you will have to make a report to that particular jail.

The short answer is "no", both are not being charged for the same call. You will need to listen carefully to the recording as the inmate MAY be calling "collect" (where you would accept the charges). But, mostly the recording is an warning of sorts letting the recipient know the call is coming from a prison or jail and asking if you want to "accept the call".  Sign up for the InmateAid Discount Telephone Service - when they call, it's

If you change your cell number to the local exchange (913) the calls will become local calls from the prison. Use Western Union and send money into the inmate's phone account and he will then be calling you at the lower rate.