[asterisk-users] LAN IAX2 trunk bad audio quality vs. LAN SIP trunk good audio quality

[Vieri]

--- On Thu, 5/13/10, Gareth Blades <list-asterisk at skycomuk.com> wrote:

> Show the details on the active
> channels when using both methods and 
> check what codecs are being used.

The audio codecs are different:

           Type: SIP
          State: Up (6)
          Rings: 0
  NativeFormats: 0x4 (ulaw)
    WriteFormat: 0x40 (slin)
     ReadFormat: 0x40 (slin)
 WriteTranscode: Yes
  ReadTranscode: Yes

           Type: IAX2
          State: Up (6)
          Rings: 0
  NativeFormats: 0x8 (alaw)
    WriteFormat: 0x8 (alaw)
     ReadFormat: 0x8 (alaw)
 WriteTranscode: No
  ReadTranscode: No

By the way, I have this in iax.conf:

[interboxIAX2]
deny=all
allow=ulaw
allow=gsm
type=friend
host=192.168.250.111
secret=mysecret
auth=plaintext
requirecalltoken=no
qualify=yes
context=mycontext
trunk=yes
username=interbox

Shouldn't the channel details report ulaw instead of alaw?

Also, if I change [interboxIAX2] and replace ulaw with alaw, the result is the same (I still experience bad audio quality).

Maybe I should try slin but how do I "force it"?

> Vieri wrote:
> > Hi,
> > 
> > I have an audio quality problem regarding IAX2. I have
> 2 Asterisk servers interconnected via 2 LAN trunks at 1Gbps
> (no nat, no firewall).
> > One trunk is SIP and the other IAX2.
> > Normally, I use IAX2 but have noticed easily
> reproducible audio quality problems (voice in/out is OK but
> there's a "third" noise overlapping with a "scratchy sound"
> as if it were some kind of interference).
> > 
> > So lately I setup calls to go through the SIP trunk
> and audio quality is OK (no "third overlapping noise").
> > 
> > This is happening between Asterisk 1.4.31 and a
> 1.2.40.
> > 
> > I'm wondering if there's something I can tweak in IAX2
> to eliminate this artifact.
> > 
> > Could the IAX2 jitter buffer between 1.2 and 1.4 be an
> issue (I believe it's enabled by default)?
> > 
> > Thanks,
> > 
> > Vieri
> > 
> > 
> > 
> >       
> > 
> 
> 
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