Webcallback issue

Hi

I want use my webcallback module to make calls like the following way:

1.- Enter the phone number (landing phone) on the webcallback box and click the button

2.- Make the call from the freepbx to selected number and then make a call to another PSTN number and pleace both calls together

My problem is when the both calls are connected I can´t hear the voice on the both ways

I use a sip trunk to make calls from the freepbx to PSTN

my configuration (GUI)

WEBCALLBACK section
Destination: Misc destination > mymobile

MISCDESTINATION section
name: mymobile
Destination: XXXXXXXXXXXXX

TRUNKS section
name: mysiptrunk
maximum channels: 2
Peer details:
host=my.domain.net
username=myuser
secret=mypassword
type=peer
disallow=all
allow=ulaw&gsm&alaw
context=from-trunk
canreinvite=no
nat=yes

What i’m doing wrong?