[Asterisk-Users] Problem with chan_iax.cimplimentationcausesbadaudio?

[Rich Adamson]

>> Thanks for the offer.  We deleted all of our Ethereal traces once we
>> switched to SIP.  On a bad call call there were tens of thousands of
>> checksum errors and packets out of sequence.  This occurred both with
>> and without IAX2 trunking and trunktimestamps.
> 
> Checksum errors- That is interesting - IAX doesn't have checksums, udp
> can though. Sounds like some aspect of IAX was interacting (in a bad way)
> with your VPN.
> 
> The out of sequence stuff could definitely be the IAX update.
> I had to add code to cope with blocks of 3 packets arriving in
> the wrong order (over a WAN) when I moved to 1.2
> 
>>
>> Complaints of poor quality were from both the agent and customer sides.
>> Mostly cutting in and out - typical of dropped packets.
> 
> Yeah, that is consistent with the checksum errors.
> 
> I'd be very interested if anyone else has packet traces that show
> this sort of problem, we are looking to deploy on IAX, and
> a bit of warning would be great.

Why does asterisk/configs/iax.conf.sample show this?

; Disable UDP checksums (if nochecksums is set, then no checkums will
; be calculated/checked on systems supporting this feature)
;
;nochecksums=no