[Asterisk-Users] Re: Polycom sound quality problems

[Eric Mason]

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:

QoS
RTP
802.1Q User Priority
	
IP ToS Minimize Delay
	Enabled Disabled
IP ToS Maximize Throughput
	Enabled Disabled
IP ToS Maximize Reliability
	Enabled Disabled
IP ToS Minimize Cost
	Enabled Disabled
IP ToS Precedence
	
Call Control
802.1Q User Priority
	
IP ToS Minimize Delay
	Enabled Disabled
IP ToS Maximize Throughput
	Enabled Disabled
IP ToS Maximize Reliability
	Enabled Disabled
IP ToS Minimize Cost
	Enabled Disabled
IP ToS Precedence
	
Other Protocols
802.1Q User Priority
	
The problem is not that it's choppy or breaks up.  Asterisk is connected 
to the phone through two 100mbit switches, so throughput isn't a 
problem.  It just sounds very distorted, like a cross between a robot 
and Donald Duck.

It really seems to be a problem with the way Asterisk is bridging the 
call from IAX to the phone.  It does SIP <-> SIP bridges (not 
reinviting) just fine.



Noah Miller wrote:
> Hi Eric -
> 
>>>> I'm having a problem with my Polycom phones and hoping someone else
>>>> has experienced the same thing: Outbound calls are fine, and inbound
>>>> calls originating from another SIP phone are fine, but inbound calls
>>>> to the Polycom phone from an IAX channel sound like you're talking to
>>>> a robot.  The person on the Polycom sounds fine to the person on the
>>>> IAX channel, however.  Inbound calls to our soft phones sound just 
>>>> fine.
>>>>
>>>> Asterisk 1.0.5 on Debian (also had the problem with 1.0 on Fedora)
>>>> Polycom SoundPoint IP500 SIP
>>>> Sixtel is the IAX provider.
>>>
>>>
>>> Check to see what codec is being used for the call.
>>> Sean
>>>
>> Default is U-law, but I also switched it to A-law with the exact same
>> results.
> 
> 
> I might check out QoS.  You can specify TOS tagging on your IAX channels 
> in iax.conf, and the Polycom phones are able to respond to TOS tagging 
> (in ipmid.cfg - or in the web interface under "Core Conf").  Maybe they 
> are are trying to do two mutually exclusive kinds of TOS tagging?  You 
> can tell the Polycom phone to just not respond to TOS.
> 
> - Noah
>