[cisco-voip] Voice quality issues with FXO ports

[Erick Bergquist]

Hi,

Having some issues with a 2800 ISR and 6 analog lines
and FXO interfaces. VIC2-4FXO and VIC2-2FXO. 

We had same problem with 2610XM router but upgraded to
2800 series for other reasons (performance, CPU, etc)
and problem continues.

The voice quality issue is every now and then, on
calls we will hear a few seconds of static, or a
whishing type sound in background. Sometimes the users
hear other noises like someone elses phone
conversation in background. Sometimes there is a high
pitched sqweaching sound briefly on calls. Sometimes
the call is mushy and like you're talking through a
wet rag. That is how one user describes the calls.

Both parties hear the whishing sound, high sqweaching,
sometimes there is dropped syllables. 

The calls are local to same subnet as Gateway and
G711. No errors on LAN, QoS is fine, etc. The users
don't have problems with calls over WAN back to HQ,
etc - just with calls on the local lines using FXO
ports.

We have adjusted input/output gains every which way
and the volume is good, etc with input gain 8 and
output attenuation of -3. 

The above voice quality issues are off and on , some
days there are no reports of issues and other days
there is a lot of reports of above. There is no echo
reported, etc and we have adjusted impediences also
with no real change. Were told the local provider
Sprint is supplying 900ohm lines and have matched
that.

The problem appears to be calls made locally or within
the same part of the state. This is in eastern NC
(Kinston). Calls made to the phone lines from other
states (LD Calls) appear to fine and problem free as
this is how I am working and testing this and every
time I call into all these lines I am not experiencing
any of the above problems. 

These phone lines have been used with a old PBX system
fine and if we plug up regular phones to the lines
without going through the routers the calls are fine
of the few dozen we made that way. 

I'm looking to see if anyone has had this sort of
issue and has any ideas on how to fix it. We've
replaced the FXO modules also. We have other sites in
area with same hardware setup and same VICs and no
problems like this at those sites. Just this one site.
The local cabling has been checked and redone as well
at the facility to rule out any problems. We are using
2 wire cables. 



		
__________________________________ 
Yahoo! Mail 
Stay connected, organized, and protected. Take the tour: 
http://tour.mail.yahoo.com/mailtour.html