[cisco-voip] Echo on IP Phones through PRI

[Axel Wilzinski]

We had a similar problem that was related to slip seconds on the T1.  It was interesting because even though the slip seconds were consistent, the echo was not.  The root of the problem was caused by not having a "network-clock-select" statement in the config.  This problem drove us crazy for a couple of weeks because we upgraded IOS and DSP firmware per Cisco's instructions to no avail.Do a show controllers t1 0/0/0 (or whatever port the PRI is on) and make sure it's clean.  You should see a lot of zero's.> Date: Thu, 10 May 2007 11:34:44 +0100> From: matt at melbourne.org.uk> To: smgustafson at gmail.com> CC: cisco-voip at puck.nether.net> Subject: Re: [cisco-voip] Echo on IP Phones through PRI> > Thanks Steve. We have an upgrade planned for our voice gateways in an> forthcoming maintenance window, where we'll try 12.4(latest) mainline.> Are you aware of any bugs which document this issue?> > Cheers,> > Matt> > On 09/05/07, Steve G <smgustafson at gmail.com> wrote:> > 12.3(14) will deffinietly give you echo issues.  it is the DSP firmware.> > either get new DSP firmware from TAC, or upgrade IOS.  I am using 12.4(8)b> > with no issues.> >> > Steve> >> >> > On 4/18/07, Matthew Melbourne <matt at melbourne.org.uk> wrote:> > >> > > We are getting sporadic issues from users on IP phones who are hearing> > > echo on external calls. From this document is would suggest that echo> > > on IP Phones is caused by hybrid echo and not any local acoustic echo.> > >> > >> > http://www.cisco.com/warp/public/788/voice-qos/echo_ipphone_gateway.html> > >> > > The MGCP-controlled voice gateways are all running 12.3(14)T7 with DSP> > > firmware 4.4.708. In CallManager (4.1(3)SR2), echo cancellation is on> > > for each port, with a "default" echo cancellation coverage of 64ms.> > > Input gain and output attenuation are set to 0dB.> > >> > > I have seen suggestions to include the "echo-cancel erl worst-case 3"> > > command on the voice ports. Can this help in situations of occasional> > > echo?> > >> > > Are there any other parameters changes which could help? Could it be a> > > code/DSP firmware issue? I haven't found a specific echo-related bug> > > relating to this particular IOS and its embedded DSP firmware.> > >> > > On occasions, the start of the call is fine but echo comes and goes> > > during the call.> > >> > > Is there a quick way of finding out which voice gateway a call is> > > terminated on (we have 8, and all could be used in a round-robin> > > fashion for outbound calls).> > >> > > Cheers,> > >> > > Matt> > >> > > --> > > Matthew Melbourne> > > _______________________________________________> > > cisco-voip mailing list> > > cisco-voip at puck.nether.net> > > https://puck.nether.net/mailman/listinfo/cisco-voip> > >> >> >> > > -- > Matthew Melbourne> _______________________________________________> cisco-voip mailing list> cisco-voip at puck.nether.net> https://puck.nether.net/mailman/listinfo/cisco-voip
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