Although calls can be monitored (and usually are), if the call was disconnected, it wasn't because you were discussing an appeal or anything else. If you accidentally hit a button on your phone, or try to do a 3 way call, these things will trigger the phone to automatically disconnect. Even if you pick up another line...that can cause it. You can contact the billing service responsible for the calls (possibly Correctional Billing Services - or call the facility and they will let you know who handles them)....and ask for a credit for the call...you also need to be aware that the calls last 15 minutes....not a second more, so if you were talking and got cut off at the 15 minute mark, that is 'business as usual'.
Please let me know if I can help further.