[asterisk-users] Occasional robotic sound while call in progress

[Andreas Sikkema]

On 1/18/11 12:01 AM, Michelle Dupuis wrote:
> We have an application that plays a variety of sound files on one leg of
> a call (generated by a call file).  We've been told that the party
> listening to the audio files intermittantly hears "robotic" sounding
> audio (on/off during the same call).
>  
> Anyone have ideas on cause?  These calls are on an internal network
> (lots of network bandwidth), and from a server running 99% idle.  Hmmmmm

I have heard/seen these kind of complaints and in my experience they
occur with _very_ low amounts of packet loss. The codec gets confused
and can't output the proper audio, just a slightly incorrect version of
it. Packet loss like this at the start of a call, which could be caused
by some form of NAT traversal via a media proxy where media is only sent
both ways when audio has been received from both endpoints, is not
unheard of.

Network bandwidth is not a very good indicator of the quality of your
network Make sure you know if there's packet loss on individual links
(managed switches FTW), what the jitter is end to end, etc.

-- 
Andreas Sikkema