[Asterisk-Users] Is my dialplan wrong?

[김대용]

Hello, users!
It is simple.
I want to make a call among asterisk and netmeeting(192.168.1.107).
chan_h323 & chan_vpb are loaded.
The call from netmeeting to asterisk(chan_vpb) is established a connection
and can communicate each other.
The call from asterisk(chan_vpb) to netmeeting is also connected, but there
is no sound even any noise.
Perhaps is my dialplan wrong?

My dialplan & configuration files are 

extensions.conf : 
[general]
static=yes
writeprotect=yes

[globals]
OUTERVPBCHAN1=vpb/1-7
OUTERVPBCHAN2=vpb/1-8

INNERVPBCHAN1=vpb/1-9
INNERVPBCHAN2=vpb/1-10
INNERVPBCHAN3=vpb/1-11
INNERVPBCHAN4=vpb/1-12

IPPHONE=h323/10.10.10.107

[vpb_default]
exten => _0,1,dial(${IPPHONE})
exten => _0,2,hangup

[h323_default]
exten => s,1,dial(${INNERVPBCHAN2})
exten => s,2,hangup

h323.conf :
[general]
port = 1720
bindaddr = 0.0.0.0
allow=adpcm
allow=ilbc
allow=alaw
allow=gsm
allow=lpc10
allow=ulaw
allow=g726
gatekeeper = DISABLE

vpb.conf :
[general]
type = v6pci
cards = 1

[interfaces]
board = 1
echocancel = on

; For OpenSwitch6; Note that V6PCI channel numbers start at 7!
context = vpb_default 
mode = fxo
channel = 7
channel = 8

mode = dialtone
channel = 9
channel = 10
channel = 11
channel = 12