[Asterisk-Users] Re: Polycom sound quality problems

[Eric Mason]

There's no transcoding going on.  It's ulaw on IAX with Sixtel and ulaw 
on SIP to the phone.  I considered that as a possibility originally, and 
even tried using GSM with Sixtel to force it to do transcoding, but had 
the exact same problem. 

The Asterisk box is a 2.4ghz P4 with 512MB RAM, doing nothing but 
Asterisk.  I have only 9 extensions.

I would think there's a possibility of packet loss on the IAX channel, 
except the other SIP phones (SJPhone softphone) work flawlessly.  Also, 
OUTBOUND calls are just fine on the Polycoms.  Only incoming calls are 
messed up.



Max W Blackmer Jr wrote:

>>I don't see any way to tell the Polycom to "ignore" QoS.  It's mainly
>>routers and switches that pay attention to QoS, the phone would just set
>>QoS on its outgoing packets.  Anyway, here's what's in the QoS section-
>>it all seems to be related to sending packets:
>>
>>    
>>
>
>It is not in the transport if it is sounding bad.... look and see if
>there is any transcoding occuring from the IAX to the SIP. What codecs
>are accepted on the AIX should be the Same codecs accepted on the SIP
>channel ... and what codects are being used on each phone. This sounds
>like a transcoding issue.
>
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