[asterisk-users] Help - Poor Voice Quality

[Gary G. Hendershot]

I have been with Teliax for some time ... Overall I like the service very
much ... The key things offered that got me to go with them (having been
with VoicePulse and BroadVoice) was live person in tech support and choice
of either SIP or IAX trunking ( I have 4xCalls with the plan I bought ) ...

However, I also had sound quality issues with them early on when I used IAX
... As soon as I switched to SIP, the problem went away and the quality was
outstanding ...

Also, the New York gateway you are using was still in BETA last time I
checked ... You might want to try using the voip-co1.teliax.com gateway with
SIP ... See how that works ... 

If not, give the tech support guys at Teliax a shot ... I have found them to
be quite responsive the few times I have needed them ...

G.Hendershot


-----Original Message-----
From: Jim Duda [mailto:jim at duda.tzo.com] 
Sent: Tuesday, February 06, 2007 8:10 PM
To: asterisk-users at lists.digium.com
Subject: [asterisk-users] Help - Poor Voice Quality

I'm struggling to get my VOIP installation to be acceptable.  I'm looking
for advice on what else I can look for.

My system:
o Teliax VOIP service, voip-ny1 proxy
o RCN Cable Internet Service (3Mbps download, 500kbps upload, 6ms average
jitter) o 3.2 GHZ P4 Server (runs asterisk, firewall, other stuff) o server
lightly loaded o Linux kernel 2.6.19.2 o Shorewall Firewall software with
QOS configured for VOIP P1 o Asterisk 1.4.0 o Sipura SPA-2000 o Grandstream
GXP-2000 o IAX connection to teliax

Outbound voice quality is many times horrible, to the point where ppl say
they cannot hear me.  The voice often drops out.  Inbound quality seems to
cut in and out too.

I downloaded the myVoipSpeed VOIP analyzer.  It indicates that I have plenty
of download and upload bandwidth.  I also have good jitter.  The tool
doeesn't find any packet loss whatsoever.

My RCN cable company cannot find anything wrong with my cable modem.  No
packet loss.  I'm supposed to be paying for 10M bit downloads, but only
getting 3M bit.

I've been on the shorewall firewall and confirmed that I have the firewall
configured properly for VOIP QOS.

I'm using the basic asterisk iax.conf setup with only those changes required
to interface with the teliax service.

I have the same issues with both the Sipura Adapter and the Grandstream
phones, however, I do believe the Grandstream appears worse at times.

I've attempted to analyze the IAX traffic using the Wireshark ethernet
protocol analyzer.  Everything looks okay best I can tell.

What else can I do to analyze why the voice quality is so bad?
What can I do in Asterisk to help track down where the problem is?

I want to make this VOIP work.

Thanks for any help.

Jim