One of the perils of running your own open source PBX is that a lot of the things that you can “just assume” about running a phone system you have to remember to think about with Asterisk. For example, today I was experimenting with the Asterisk Manager API and used it to open a channel to my outside POTS line. I then got distracted, and forgot to “hang up” the channel, so the line stayed “in use” for 3 or 4 minutes until I realized the error of my ways.

BTW, the solution to the immediate problems was to connect to the Asterisk CLI, and issue the command “soft hangup Zap/1-1”.