asterisk users - Jul 2006 - tdm04b strange noise when answering calls

Hi,
I have a tdm04b (4fxo) with channels 1 and 2 attached to the pstn.
When someone dials the numbers associated to the pstn the asterisk
aswers but I start to hear a tone, high-pitch like a fax.
here is the config:

extensions.conf
[dialinc]
exten => s,1,Answer()
exten => s,2,Playback(hello-world)
exten => s,3,Hangup()

zapata.conf
[trunkgroups]
[channels]
usecallerid=yes
hidecallerid=no
callwaiting=no
threewaycalling=yes
transfer=yes
;echocancel=yes
;echotraining=yes
context=mefdialinc
signalling=fxs_ks
channel=1-4

output of the CLI:
Verbosity was 17 and is now 36
Starting simple switch on 'Zap/2-1'  ****HERE I START TO HEAR THE HIGH
PITCH TONE
Jul  4 22:50:12 WARNING[6658]: chan_zap.c:6135 ss_thread: CallerID
returned with error on channel 'Zap/2-1'
    -- Executing Answer("Zap/2-1", "") in new stack
    -- Executing Playback("Zap/2-1", "hello-world") in new
stack
    -- Playing 'hello-world' (language 'en')
    -- Executing Hangup("Zap/2-1", "") in new stack
  == Spawn extension (mefdialinc, s, 3) exited non-zero on 'Zap/2-1'
    -- Hungup 'Zap/2-1'
centos*CLI>

Where can this high pitch noise come from?

Thanks,


-- 
------------------------------------------------------------
Erick Perez
Panama Sistemas
Integradores de Telefonia IP y Soluciones Para Centros de Datos
Panama, Republica de Panama
Cel Panama. +(507) 6694-4780
------------------------------------------------------------

> Starting simple switch on 'Zap/2-1'  ****HERE I START TO HEAR THE
HIGH
> PITCH TONE
> Jul  4 22:50:12 WARNING[6658]: chan_zap.c:6135 ss_thread: CallerID
> returned with error on channel 'Zap/2-1'
>    -- Executing Answer("Zap/2-1", "") in new stack
>    -- Executing Playback("Zap/2-1", "hello-world") in
new stack
>    -- Playing 'hello-world' (language 'en')
>    -- Executing Hangup("Zap/2-1", "") in new stack
>  == Spawn extension (mefdialinc, s, 3) exited non-zero on 'Zap/2-1'
>    -- Hungup 'Zap/2-1'
Looks to me you are catching the end of the Caller ID signalling.  Perhaps 
your telco is not behaving.  Try putting a wait in your dialplan before 
answering.  This should workaround the problem, or at least it has worked 
for me in the past.

Regards,


Raymond McKay
President
RAYNET Technologies LLC
http://www.raynettech.com
(860) 693-2226 x 31
Toll Free (877) 693-2226