Isdn noise on the line

wedge1988

Hi all,

when I make a phone call from the outside world over our isdn lines (isdn2e) the call comes in all echoey and ends up getting interference like when you hold a microphone too close to a speaker. Any ideas what this is? I've looked at the noise on the line and it doesn't do much changing the settings..

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shodown

show controllers to see if you have any errors on it. If you don't check your with service provider to see if its a SIP trunk back to them in which case you can have some Quality of service problems. Also if your ISDN line is not local to you you may want to give your own network a QOS check. Hope this helps.

wedge1988

It could be qos, I'll have to test it soon and get back to you, thanks for the heads up. Thought it may be though, I have a 6509 which doesn't support auto qos so looks like I have some reading to do! (All other switches support auto qos)

TheNewITGuy

echo can anyone?

wedge1988

It's been a while, granted. I tested it out today. I managed to get the DDI inbound working (no luck mapping for outbound yet) and the echo is still there. I plugged a phone directly into the UC520 box and it still does the echo so im pretty sure it's not the qos.

Any other advice>? Cisco seems to say reduce the noise levels on the voice ports?

wedge1988

So that you are all aware of the solution, here it is: You have to use the command

compand-type a-law

under the correct BRI voice-port.