Garbled Audio


#1

Hi folks - hope you can help with this one…

The Asterisk server in one of my offices is experiencing bad audio problems - when they call out to anyone - the audio starts to sound broken up - garbled - like talking underwater. They are running exactly the same version I am 1.4.24.1 the only difference I see is in their configs which I did not set up since I inherited these and were in place.

I don’t know where to look so I am starting with the config files. Their Extensions.conf file has this context…
[bandwidth]
exten => _+1.,1,Set(DID=${EXTEN:2})
exten => _+1.,n,Goto(fromtrunk,${DID},1)

and the sip.conf file shows …
[bandwidthPri]
host=216.82.224.202
port=5060
type=peer
allow=ulaw
dtmfmode=rfc2833
reinvite=no
canreinvite=no
context=bandwidth
nat=no

[bandwidthAlt]
host=216.82.225.202
port=5060
type=peer
allow=ulaw
dtmfmode=rfc2833
reinvite=no
canreinvite=no
context=bandwidth
nat=no

[bandwidthOut]
host=216.82.225.202
port=5060
type=peer
allow=ulaw
dtmfmode=rfc2833
nat=no
reinvite=no
canreinvite=no

Also - when a call is made from their system I see i.e. 8005551212@bandwidthout in the CLI as I watch to see what is happening.

None of my other systems are configured to show "BandwidthOUT - ALT or PRI in any config file.

I believe the IP address shown is the carrier that office is using ( bandwidth.com )

I am trying to isolate the sound issue and this is the only difference I see on their system.

I don’t even know if this is where to look but figured it was a start.

I do hope you can help,

Thank you.


#2

For start check the network latency and jitter. You can do this by pinging the Asterisk server from the network where the IP Phones are connected to.

Secondly, you can do a packet capture of an active call (using tcpdump) on the Asterisk server and try to decode it and listen to the audio with the Wireshark tool. You will quickly see where is the source of the bad audio.


#3

That sounds like a plan !!! Thank you - I will do that !!! - in the meantime - I did notice the QoS service on their router looked like it was set on the low side - I’m not an expert on that but was wondering if that could contribute to their issue?