Bad quality - even locally

Hello

asterisk 1.4.0, i have quality problems even calling locally (100Mbit network).
I registered my softphone (idefisk) as IAX2. I call other softphones in my company and external numbers in the internet.
When i called such external number with bad quality i had in logs:

[Mar 20 17:52:23] VERBOSE[22474] logger.c: – Executing [0801300800@numberplan-custom-1:1] Dial(“IAX2/006-2”, “IAX2/trunk_t2_test/0801300800||r”) in new stack
[Mar 20 17:52:23] VERBOSE[22474] logger.c: – Called trunk_t2_test/0801300800
[Mar 20 17:52:23] VERBOSE[22397] logger.c: – Call accepted by 194.9.78.16 (format ulaw)
[Mar 20 17:52:23] VERBOSE[22397] logger.c: – Format for call is ulaw
[Mar 20 17:52:23] VERBOSE[22474] logger.c: – IAX2/trunk_t2_test-7 is ringing
[Mar 20 17:52:28] VERBOSE[22474] logger.c: – IAX2/trunk_t2_test-7 answered IAX2/006-2
[Mar 20 17:52:28] VERBOSE[22474] logger.c: – Operating with different codecs 2[0x2 (gsm)] 4[0x4 (ulaw)] , can’t native bridge…
[Mar 20 17:52:28] DEBUG[22403] chan_iax2.c: Ooh, voice format changed to 4
[Mar 20 17:52:28] DEBUG[22397] chan_iax2.c: Ooh, voice format changed to 2

What does it mean “can’t native bridge” ? Is it the case ? (conversion from different codecs?).

When i tried to call locally my mailbox:
[Mar 20 18:03:47] DEBUG[22402] chan_iax2.c: We don’t do requested format gsm, falling back to peer capability 1550
[Mar 20 18:03:47] VERBOSE[22402] logger.c: – Accepting AUTHENTICATED call from 192.168.100.165:
> requested format = gsm,
> requested prefs = (),
> actual format = gsm,
> host prefs = (),
> priority = mine
[Mar 20 18:03:47] VERBOSE[22565] logger.c: – Executing [113@numberplan-custom-1:1] VoiceMailMain(“IAX2/006-5”, “”) in new stack
[Mar 20 18:03:47] DEBUG[22565] app_voicemail.c: Before ast_answer
[Mar 20 18:03:47] DEBUG[22565] channel.c: Scheduling timer at 160 sample intervals
[Mar 20 18:03:47] VERBOSE[22565] logger.c: – Playing ‘vm-login’ (language ‘en’)
[Mar 20 18:03:47] DEBUG[22396] chan_iax2.c: Ooh, voice format changed to 2
[Mar 20 18:03:49] DEBUG[22565] channel.c: Scheduling timer at 0 sample intervals
[Mar 20 18:03:49] DEBUG[22565] channel.c: Scheduling timer at 0 sample intervals

This time the quality was much worse, i baraly could understeand what vm-login said. This is made locally (100Mbit network), strong client and server computers.
What is the cause ?

Thanx

You are not passing the codec allowed in the exten setup
requested prefs = (),

What about zaptel / ztdummy?

IAX needs a timing device. (zaptel / ztdummy)

test with SIP phone

I do not have zaptel on my server (yet).
I also do not have SIP phones yet.
But i found it was the problem with the softphone on one of my linux machines
(other works fine).

Thanx