[Asterisk-Users] a couple of questions

[Ira]

I've been using * for about 3 weeks now next to my analog phones and 
I've now got enough SIP phones I can consider unplugging the analog 
ones.   I have 4 incoming analog lines into a TDM400 with 4 FXO 
ports. I've a couple of things left to figure out, but the hardest 
one seems to be implementing flash so I can get to call waiting 
calls. I think I've read every link to flash on the wiki and yet, I 
can't get a decent solution.  What I have now is:

exten => _6[0-2][0-4],1,Flash()
exten => _6[0-2][0-4],2,Dial(SIP/1${EXTEN:1},,rtT)

which works but the first caller hears MOH until the flash and they 
then they think they've been hung up on.  Also, you need to know 
which SIP line you're dialing from so it can dial back correctly. Is 
there any way to get the SIP extension that called this macro?

I've also tried:

in extensions.conf
[context]
exten => s,12, set(DYNAMIC_FEATURES=zapflash)
exten => s,13,dial(${zaino_in},400,tTj)

in features.conf
[applicationmap]
zapflash => *3, callee, flash

But that seems to do nothing either.

I'm sure I'm just missing something subtle, but a week of struggling 
and I can't figure it out.

Thanks so much, Ira