asterisk users - Nov 2004 - Grandstream BT100 - Failed to write frame

Hi everyone,

  I'm having problems with Playback() on a Grandstream Budge Tone-100.
Every time Playback is used I get the following messages:

WARNING[229388]: file.c:550 ast_readaudio_callback: Failed to write frame
  == Spawn extension (from-sip, 5555, 1) exited non-zero on
'SIP/2002-559c'

I tried pretty much every codec on the phone with no succes.

I'm using: Asterisk CVS-D2004.10.25.17.09.17-11/04/04-12:25:54
GrandStream Firmware: Program--1.0.4.65

sip.conf entry for the BT-100 Phone:

[BT100]
type=friend
context=from-sip
username=2002
fromuser=2002
secret=123456
host=dynamic
nat=no


The grandstream phone and asterisk are on the same lan.

Thanks a lot,
Dave