uc520 noise on line

[jjoseph01]

All, I have another issue with noise on a line. This can be either internal calls or internal to external calls, where they hear a sound like "sssshhhhh" (like an ocean sound, but constant). Anyone know how to get rid of something like that? Much appreciated.

[jjoseph01]

Yeah, it will be on Monday, as they are gone now for the weekend. Thanks all, Ill get back with you.

[jjoseph01]

All, my apologies on this one. I have talked to the customer again today on this issue. It turns out the customer did not tell me the truth on all of the symptoms. It turns out that the only time they hear the noise is when they are on a PSTN call, NOT INTERNAL calls. Again, I apologize for wasting everyones time, Im as frustrated as you guys are. They told me on 2 different occasions what has been stated, then today they told me something different. I questioned them on it and they act like "oh well". Thanks for everyones input. I say its the phone company's issue.

[paolo bevilacqua]

Do not worry, this happens all the time expecially with PBX customers.

Before alerting telco I recommend you follow these steps to determine the ideal impedence settings of the lines, use the tone sweep method:

http://www.cisco.com/en/US/tech/tk652/tk701/technologies_tech_note09186a0080477a06.shtml

Please remember to rate useful posts with the scrollbox below.

[jjoseph01]

ok, I finally have a grip on what the issue REALLY is. I drove up there to this location, an hour away, to find out exactly what the deal is. Here is what I found:

All phones, not just one type of phone, have this issue. The issue is the sound of "white noise", is what I know it as. Its relatively loud when the call out/in from/to the PSTN takes place. No, it doesnt happen at all internally, but every call to the PSTN, or from the PSTN, has this sound. Whats odd is that when I put my analog phone directly to the PSTN (by unplugging it from the uc520 and plugging it directly to the anl phone), I do NOT hear the white noise sound. I even took an extra uc520 we had laying around with me, put it in place, and still the same issue. There is this document out there about troubleshooting sounds like static, crackling, popping, etc. They mention VAD, of which Im not sure I know what that is exactly. Cisco TAC mentions firmware still. I cant hardly believe that, since its on all types of phones, plus the analog phone when connected to the FXS port. I upgraded the IOS today, with no success in fixing it.

Anyone know anything about either getting rid of the "white noise" or turning down the volume of it? Much appreciation to all for helping. Id ALMOST give a reward to get this issue past me.

[jjoseph01]

To add to what I just said above, here is that link I was referring to.

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_white_paper09186a00801545e4.shtml#stat

[paolo bevilacqua]

Hi, please follow the steps to configure the line, here is the link again:

http://www.cisco.com/en/US/tech/tk652/tk701/technologies_tech_note09186a0080477a06.shtml

[jjoseph01]

Ok, I have to admit, its a little over my head, but I can understand the tests and will do this. Thanks, Ill let you know.

[Nicholas Matthews]

If you want to prove it's not the firmware of the phones, do the last step provided in my post above. Decode the audio stream and listen to it (it's fun! I swear!).

Otherwise you will need to inspect the FXO line - ask the TAC engineer to get a PCM capture and you may want to run an impedance test on the line.

Place a call, and put both sides on mute. Then use this exec command:

test voice port 0/1/0 thl verbose

-nick

[jjoseph01]

ok, I did this test. Any setting just made things worse or stayed somewhat the same. Also, I did the packet capture and listened to the audio. In the audio from the capture, you can not hear the white noise at all. Weird.

[paolo bevilacqua]

Back to square 1, does it happens with the 7931 also, or only the 500 phones ?

[jjoseph01]

Yeah, it does happen on both the 524 phone and the 7931 phones. I went up there an tested these myself to verify, since I kept getting inaccurate information from the customer. But, here is the funny thing, it also happens when I plug an analog phone into the FXS port as well. Thats why I thought it might not be a firmware issue. Recap on some things Ive done:

1. Upgraded the IOS to cme7.x

2. put the config on another uc520

3. took a 524 phone of mine and put it on my uc520 with thier config

4. done the voice line tests as recommended by bevilacqua (cool tests by the way)

5. done the packet capture off the uc500, and listed to the audio (which does not produce the sound)

6. put the analog phone on the FXS port (I do hear the white noise on it)

7. Ive tried the max conf x gain command (hmmmm. I just thought maybe I should run that number down to something like 2 and give it a shot) Any thought on that?

[paolo bevilacqua]

Hi, last thing before this is given to the TAC, FW upgrade for the phones.

[slongewa]

Were you ever able to resolve this issue? I'm running into a similar issue with one of my uc520s and was wondering if you had been able to resolve it yet.

Thanks,

Steve

[Nicholas Matthews]

If you don't hear it in the packet capture that leads to a phone problem.

Troubleshoot the endpoint, unless you've got a codec negotiation failure (like using g711ulaw instead of g711alaw).

-nick

[jjoseph01]

No, I have not resolved this yet. I still have to take the time to go out and load the new firmware. Still not resolved yet.