VICIDIAL and app_conference
(1.2 tree) EXPERIMENTAL!!! 

app_conference offers the plusses of being able to do conferencing
without any zaptel hardware or timers as well as doing native codec
streaming, meaning no manditory downsampling to slin like meetme.
These two features alone mean a rather significant performance boost
to companies who only use VOIP for agents and trunks as well as not
requiring the cost of zaptel hardware or the nightmare of getting
ztdummy to work on some systems.

As of right now, I have a test system fully up and running using
app_conference with VICIDIAL on Asterisk 1.2.8. I have made several
modifications to the app_conference code to make it more of a drop-in
replacement for meetme so that it does not require any changes to the
VICIDIAL codebase. I have added entry and exit sounds(slightly
different from meetme's) as well as "only one in this conference"
message in addition to changing the default member type to speaker(S).
So far I have tested with IAX and SIP channels only and everything
works just like on meetme but I have not done any capacity testing or
tested it in production yet.

If you want to use app_conference instead of meetme for VICIDIAL then follow these instructions:

cd /usr/src/asterisk
wget http://www.eflo.net/files/VD_app_conference_0.6.zip
unzip VD_app_conference_0.6.zip
cd app_conference
make clean
make
make install


In your extensions.conf file you would replace these lines:
exten => 8600051,1,Meetme,8600051
exten => 8600052,1,Meetme,8600052
...continue through 8600100...
exten => 78600051,1,Meetme,8600051|q
exten => 78600052,1,Meetme,8600052|q
...continue through 78600100...
exten => 68600051,1,Meetme,8600051|mq
exten => 68600052,1,Meetme,8600052|mq
...continue through 68600100...


with these lines:
exten => 8600051,1,Conference(8600051)
exten => 8600052,1,Conference(8600052)
...continue through 8600100...
exten => 78600051,1,Conference(8600051|q)
exten => 78600052,1,Conference(8600052|q)
...continue through 78600100...
exten => 68600051,1,Conference(8600051|Lq)
exten => 68600052,1,Conference(8600052|Lq)
...continue through 68600100...

NOTES:
Here are the possible feature flags for this version of app_conference:
          o M: Moderator (presently same as speaker) [default]
          o S: Speaker
          o L: Listener
          o T: "Telephone caller" (just for stats?).
          o V: Do VAD on this caller
          o D: Use Denoise filter on this caller. 
          o d: Send manager events when DTMF is received.
          o q: Do not play enter or exit sounds.
          o i: use inband dtmf broadcast.
          o t: use rfc dtmf signal broadcast.

COMPILE NOTES:

Some Makefile alterations may be necessary for your system:

From Alek Barkley:
I am running FC4 with latest updates ( 2.6.16 kernel )
My CPU is AMD K6 and GCC 4.0.2.

I edited Makefile in app_conference distribution.
To enter CPU architecture in my case -march=k6
========================================================
PROC = k6
# this is fun for x86
#CFLAGS += -march=pentium3 -msse -mfpmath=sse,387
CFLAGS += -march=k6
===========================================================