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New Member

Nois in the pstn line

Hi all

I am having little weird problem that when I am using the pstn line direct means connect to direct telephone the voice is clear in calling and receiving call.

But when I am connecting it to uc520 it give some noise like ‘chha ,chha ‘ in between the voice

Which make it hard to understand the auto attendant message and also when I place a call this noise there  like chha ,chha in between the voice there is any way to remove this noise

8 REPLIES
New Member

Re: Nois in the pstn line

Hi Majid,

Is this using the in-built FXO ports or is this an add-on VIC card?

I have had this problem before and after replacing 2 systems the problem didn't go away until the third one, still to-date I have no clue what caused it and neither did TAC, it was one of those green gremlin problems.

Does the noise happen on incoming only or can it occur on outgoing as well?

Cheers,


David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *
New Member

Re: Nois in the pstn line

thank you  David.for ur support

the problem with bulit in card and it happens both incoming and outgoing

i do not know why cisco does not slove this  ,i am having other customers and really i am afraid to sell uc560 again unless this problem slove from cisco

Re: Nois in the pstn line

3 things that I know of you could try.  I would try changing the impedance first:

voice-port 0/1/0

impedance (value)

impedance values to try are 600r and 900r that I've used successfully.  600 ohms is the default.  You can check the current impedance value with the "show voice port" command

You can also try changing the ouput attenuation and input gain if the problem is volume related:

voice-port 0/1/0

output attenuation (value)

input gain (value)

Regards,

Adam Compton

New Member

Re: Nois in the pstn line

Hi Majid,

Is the noise like the following examples?

  • White Static noise, similar to that of your TV going to a channel that does not exist?
  • Is it static noise with a subtle hint of crackling in it?
  • Is the Noise a scratching noise with a resemblance to a rumbling noise (Faint rumblings)?

Also what are the full set of symptoms?

  • Does the voice fade in an out?
  • Does the noise cut the voice of the far end off?
  • Does the noise come in over the top of the far end and then fades away?
  • Is it worse on the outgoing call or on the incoming, or is it equally as bad on both (This is important as the impedance can be different depending on your carrier for incoming or outgoing)

You can make the suggested changes as the post above, however I would caution you on doing so without having someone from support on the other end of the phone, these changes require CLI modification in most cases (Unless recently introduced into CCA) and these changes can incur other issues such as heavy feed back, echo and other unwanted attributes. Having a Cisco tech on the other end of the line helping you out with diagnosing this problem is the best advise I can give you on this, unless you are very good with CLI work and can either revert the changes quickly and know how to read any of the debug messages, it is very very very important you understand what the changes may do to the service or the system, making changes blindly will often cause you more grief than what you are experiencing now.

If you havent logged a SMB support request (OR TAC if this is a CLI only system) then i would encourage you to do so, especially if this is a

production system, the longer you take to do it the longer the client will have to deal with the problem.

Cheers,

David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *
New Member

Re: Nois in the pstn line

the issue i am having as u said White Static noise, similar to that of your TV going to a channel that does not exist

this perfect description i think it would have taken me  while to write this ,Thanks,

CCA 3 have possibility to modify the value without need for CLI, i am trying but with the value still no use

regarding open ticket ,this can not  be done  because the box is uc520 and it is no supported by small business division of cisco so either we have to get support from distributor (which will not help)

or purchase smart net

really sad storyyyyy , any help will be appreciated

New Member

Re: Nois in the pstn line

Hi Majid,

If you private message me details to log onto the system remotely I would be happy to look at it and see if I can assist you with the problem.

I would need either of the following:

  • Teamviewer access (www.teamviewer.com) which would allow me to log onto your computer... or
  • SSH access with a temp username and password with executive access

If the problem is the same as the ones I have experienced in the past, then it is highly unlikely I am going to be able to resolve it, but still I am more than happy to investigate it for you

Let me know what you want to do.

Cheers,

David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *
New Member

Re: Nois in the pstn line

hi David

I have change all values

impedance (value)
output attenuation (value)

input gain (value)

and i checked all combinations without any use the tension is when customer plug his 1$ telephone and connect to pstn line and make call the voice

is very clear ,i am fed up cisco  , could you tell me how u solved your problem what you did exactly please ,customer frustrated and i am done with cisco

this lines from Saudi telecom company STC.

New Member

Re: Nois in the pstn line

Hi Majid,

There are a few things to look at here and also possibly do.

  1. Fault Elimination Process:
    If these are in-built FXO ports i would suggest trying each trunk line in an individual port, one at a time so take line-1 plug it into FXO-0 and make a test call, if there is noise on the line then write it down so you know and label that line... Then move onto the next line and the next line etc..etc.. But once you have finished all the lines on FXO-0 move onto the next FXO port, at each step taking notes of the noise and the symptoms, if they are different on each port you need to write down what the differences are, make sure you cycle between each phone line on a one-by-one basis through each port... This is the power of elimination and it can work wonders with fault finding!!

  2. Work Around The Issue:
    If the onboard FXO ports are in-deed faulty and you do not have SMARTnet on the system you can do the following: Purchase another FXO card and put that into the expansion slot, or borrow one from someone and do some tests and see if the issue is still there (Maybe ask the distributor if they can loan you one??), this may expose a larger problem. Consider migrating to ISDN and purchase a 2 Port BRI Card for the expansion module, however I do not know what STC provide so this is just a suggestions, however either one of them is still not the best option, consider option 3 then

  3. SMARTnet on the device:
    For what you get with SMARTnet the costs are very small, with the UC-520 you can get TAC support or if you want to go CCA only then you can get SMB support, either one is good, TAC is best if you want to go CLI only and may be quicker in resolution of your fault at this point in time. Also with SMARTnet if the system is faulty I.E it is not the FXO card (Inbuilt or otherwise) that is the problem and something more sinister like the DSP or capacitors, then fixing this yourself is not achievable, and having not just support but warranty over the entire system is the best outcome you can achieve.

None of these suggestions are going to eliminate your concerns or the problem unless they are acted upon, but if you have already diagnosed this end-to-end and have pulled out enough hair, at which point do you decide to step away from it and take the path that will cost you money up front? But maintain your sanity and the clients if this is a production system?? You have to consider alternatives if you want to get past this problem, fixing yourself into a corner will not solve it I promise you this.

Speak to your local Distributor and ask them if they can also provide you with technical assistance, if the UC-520 is new then it is also under warranty and if a fault is present then this needs to get resolved.

I hope you find a solution to your problem, and I am sorry you are in this position it is not a nice thing to go through and I know how you feel.

Cheers,

David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *
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