Testing client dial to playback / echo no response

I just try install fresh asterisk 1.2.14-32 at centos 4.3 with kernel version 2.6.9-42 and zaptel-1.2.12-26

i write a simple iax.conf like this

and add simple dial plan at extensions.conf like this
exten => 1234,1,Dial(IAX2/1234,20)
exten => 1234,2,Voicemail(1234)

exten => 1235,1,Dial(IAX2/1235,20)
exten => 1235,2,Voicemail(1235)

exten => 1232,1,Answer()
exten => 1232,2,Playback(hello-world)
exten => 1232,3,Hangup()

note: client using idefisk and already try connect at asteriskguru.com and voiprakyat.or.id without no problem

calling to exten 1232 no response at all (not hear any playback sound), asterisk log with verbose level 6 show this message
Verbosity was 5 and is now 6
– Accepting UNAUTHENTICATED call from
> requested format = gsm,
> requested prefs = (),
> actual format = gsm,
> host prefs = (gsm),
> priority = mine
– Executing Answer(“IAX2/”, “”) in new stack
– Executing Playback(“IAX2/”, “hello-world”) in new stack
– Playing ‘hello-world’ (language ‘en’)
– Executing Hangup(“IAX2/”, “”) in new stack
== Spawn extension (default, 1232, 3) exited non-zero on ‘IAX2/’
– Hungup ‘IAX2/’

Could be that you don’t have a GSM version of hello-world to play?

This problem is solved, cause problem is NAT issue