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New Member

PRI echo

We have a new CCM 5 installation with a pri...the customer has reported problems with echo...we are in the process of getting data from calls that have echo but since the problems are sporatic we are not able to get alot of good data...

This is the output of a show call active voice a call that had a test tone generated on it...

TxDuration=114875 ms

VoiceTxDuration=114875 ms

FaxTxDuration=0 ms

CoderTypeRate=g711ulaw

NoiseLevel=-82

ACOMLevel=63

OutSignalLevel=-15

InSignalLevel=-79

InfoActivity=1

ERLLevel=45

EchoCancellerMaxReflector=4

The setting on voice-port are input gain -3 ...my main issue is why is the

InSignalLevel=-79 such a large number...I would think this would -18...

From my understanding echo on a pri is not common...am I missing something...

Joe

7 REPLIES
New Member

Re: PRI echo

What kind of voice gateway and version of IOS are you running?

New Member

Re: PRI echo

Cisco IOS Software, 2800 Software (C2800NM-SPSERVICESK9-M), Version 12.4(3g), RELEASE SOFTWARE (fc2)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2006 by Cisco Systems, Inc.

Compiled Mon 06-Nov-06 02:36 by alnguyen

ROM: System Bootstrap, Version 12.4(13r)T, RELEASE SOFTWARE (fc1)

bk0014_Main_2811 uptime is 8 weeks, 22 hours, 3 minutes

System returned to ROM by power-on

System restarted at 17:30:33 EST Wed Jan 17 2007

System image file is "flash:c2800nm-spservicesk9-mz.124-3g.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

Cisco 2811 (revision 53.51) with 251904K/10240K bytes of memory.

Blue

Re: PRI echo

Joe,

The -79 is actually a very low level as the reference is 0db. The OutSignalLevel is your test tone.

On our IOS gateways with PRIs I have found that the worst case erl needs to be changed from the default 6db to 3 in order to eliminate all echo problems. This means that a echo signal 3db or more below the transmit level will be cancelled.

voice-port 1/0:23

echo-cancel erl worst-case 3

It is the far end termination of the call that causes echo. So if you place a call over your PRI that terminates on another PRI it would be unusual for you to hear echo. If you place a call over your PRI that terminates on an analog line with bad return loss (high reflection) you will hear echo.

Here is a good doc:

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml

Please rate helpful posts.

Dave

New Member

Re: PRI echo

Joe,

I've got the same sporatic echo issue to calls to/from a PRI. I am using a 2821 w/12.4(3g). I am working through a TAC case, and have already been through the playing with input gain, and output attenuation. I have also been through the different echo cancel settings.

Have you had any luck figuring this out?

New Member

Re: PRI echo

Go into your router and do:

show voice dsp detailed. You will see a version of your DSPWare firmware. If it is 4.4.19 or prior, there is a known bug that causes echo under certain conditions.

New Member

Re: PRI echo

I noticed the bug when started troubleshooting this issue...unfortunately we are not affected:

DSP DSP DSPWARE CURR BOOT PAK TX/RX

TYPE NUM CH CODEC VERSION STATE STATE RST AI VOICEPORT TS ABRT PACK COUNT

===== === == ======== ======= ===== ======= === == ========= == ==== ============

C5510 001 01 {flex} 4.4.20 alloc idle 0 0 0/0/0 02 0 5734/0

C5510 001 02 {flex} 4.4.20 alloc idle 0 0 0/0/1 06 0 2726/0

C5510 001 03 {flex} 4.4.20 alloc idle 0 0 0/0/2 10 0 2956/0

C5510 001 04 {flex} 4.4.20 alloc idle 0 0 0/0/3 14 0 2394/0

Thanks,

Joe

New Member

Re: PRI echo

Joe,

My nearly identical problem with a 2821 and 12.4(3g) was resolved by moving to 12.4(7e). I've gone almost 4 full business days without hearing of any echo. I was hearing 2-3 consistent reports of echo each day before this IOS upgrade.

http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified%20Communications%20and%20Video&topic=IP%20Telephony&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1dde2b48/12#selected_message

Good luck.

Jeff

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