[asterisk-users] One Way Audio Problem

[GNUbie]

Hello all,

I've been lobbying for some time at the #asterisk IRC channel. Until
now, I still can't find a solution to my one way audio problem. I
rebuilt the Asterisk-1.4.21.2 from the Debian Testing repository on my
Debian Etch. I got a Digium TDM400P with 1 FXO (channel 4) and 1 FXS
(channel 1). My SIP extension phone located inside the LAN is a SNOM
300 IP phone.

This one way audio problem only happens when the SIP extension phone
(let's call it the CALLER) places an outbound call to a mobile phone
or analog telephone (let's call it the CALLEE) via FXO/POTS. The
CALLER can hear the CALLEE's voice but the CALLEE cannot hear the
CALLER's voice. I used this command "ztmonitor 4 -vv -f /tmp/test.raw"
to monitor the RX/TX but the TX is totally zero. Below is a sample
output of the ztmonitor command:

- - - < s n i p > - - -

# ztmonitor 4 -vv -f /tmp/test.raw
Output to /tmp/test.raw
Run e.g., 'sox -r 8000 -s -w -c 1 /tmp/test.raw /tmp/test.raw.wav' to convert.

Visual Audio Levels.
--------------------
 Use zapata.conf file to adjust the gains if needed.

( # = Audio Level  * = Max Audio Hit )
<----------------(RX <----------------(TX
 ###############*
        Rx:   718 (  718) Tx:     0 (    0)

- - - < s n i p > - - -

Anyone can help me here?

Thank you in advance.

Regards,

GNUbie