[asterisk-users] [Dahdi 2.4.0] Flash() hangs up

[Gilles]

Hello

	I need Asterisk (1.4.39.2) to simulate a flash hook (ie. hitting the
"R" key on European handsets) so I can put a call on hold, dial a
second number, and set up a conference call.

By default, linux/include/dahdi/kernel.h sets the flashtime to 750ms,
which appears to be too long for European telcos, as they seem to
expect a line cut of about 100ms.

After editing the DAHDI_DEFAULT_FLASHTIME accordingly, I
recompiled/upgraded Dahdi, and ran the script, but Flash() still hangs
up the call:

===========
[from_fxo]
exten => s,1,Wait(2)
exten => s,n,Set(GLOBAL(CID)=${CALLERID(num)})
exten => s,n,Hangup()

exten => h,1,system(/var/tmp/test10.lua ${CID}&)

[callback]
exten => start,1,NoOp(In callback, CID is ${CID})
;how to wait until remote phone picked up?
exten => start,n,Wait(5)
exten => start,n,Answer()
exten => start,n,Playback(please-wait)

;HERE Dahdi hangs up instead of getting a dialtone
exten => start,n,Flash()
exten => start,n,Dial(Dahdi/1/{GSM})
exten => start,n,Wait(5)

exten => start,n,Hangup()

;0 - Failed (not busy or congested)
;1 - Hung up
;3 - Ring timeout
;5 - Busy
;8 - Congestion
exten => failed,1,NoOp(Reason call failed is ${REASON})
===========

Has someone successfully gotten Asterisk/Dahdi to use two-way calling?
Should I use another function than Flash()?

Thank you.