You have to call the institution and speak to the "case manager" or "counselor" that oversees your inmate's programming. They can unblock the line for you.
https://www.inmateaid.com/ask-the-inmate/my-boyfriend-is-currently-locked-up-i-accidentally-blocked-the-calls-i-have-money-on-my-phone-i-just-want-to-unblock-the-calls-please-help-what-do-i-do#answer
Accepted Answer Date Created: October 17,2018