I think you may try to save uuid somewhere in database (for exapmle with LUA) while call is in progress, and when you need to do something, call sched_del and sched_hangup using API call or EventSocket.
This is that i'll try.
In my view, and with my experiance it is not a good idea to be connected to FS all time.
Why? For whole call life control is good approach, because external application know all information about call state and events. Or all events external application, that receives and fires events to FS - this is my way.
Better to use one time connection to execute some commands.
Hmm, this takes extra overhead for creation\closing connections. By the way, for outbound socket connection FS use persistent connection or per event connection ?