You might have pushed the wrong number on the phone when accepting the call. If you accidentally block your inmate form calling, the system won't let him dial through. This is a measure to protect citizens from being harassed. To reverse this, you will need to call your inmate's counselor and possibly the phone service at the prison to get the block lifted.
https://www.inmateaid.com/ask-the-inmate/what-happens-if-i-accidentally-block-my-inmate-s-call-how-do-i-fix-it#answer
Accepted Answer Date Created: February 13,2016