asterisk users - Dec 2003 - Need advice with "free line" notification

I've been messing around with a "free line" notification where an
extension is dialed for a second when a line becomes available.  I
can't seem to get the "h" extension to continue when the local
party
hangs up.  I've seen references to other people having the same
problem in the list archives, and the solution presented was to use
AGI.

I've tried dialing through AGI, and through the Dial application.
They both seem to get executed, but are killed before finishing the
job:

exten => h,1,AGI(dial.agi)
    -- Executing AGI("SIP/111-b1fa", "dial-117.agi") in new
stack
    -- Launched AGI Script /var/lib/asterisk/agi-bin/dial-117.agi

exten => h,1,Dial(SIP/117,1)
    -- Executing Dial("SIP/111-5d68", "SIP/117|3") in new
stack
    -- Called 117

The only way I can get it to work is to have the AGI script write a
temporary file that is parsed by a cron job to call Asterisk from the
command line ( asterisk -r -x "Dial 117@local" ) which is not very
clean, and I don't have very accurate control of the ring duration.

Has anyone done this?

Thank you,

Barton