7920 noisy sound with OffNet Call

Unanswered Question
May 7th, 2007

I have deployed the Cisco Aironet Access-Points, Call Manager 5.0(4) and we have registered a few Cisco 7920 IP Phones.

When calling each other [OnNet call] from 7920 Phones the voice quality is good and we experience no problems.

However when a call is initiated from the 7920 to the PSTN/GSM [OffNet] or vica-versa, i hear a "strange" clicking noise on the 7920 through the duration of the call.This sound start when I talk only and stop when I listen .

I have the lastest firmware running on the Cisco 7920 (4.0-03-01) and the Voice port configuration is :

voice-port 0/0/0

cptone BR

connection plar opx 5000

caller-id alerting dsp-pre-allocate

Any advice for this problem .

I have this problem too.
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yhab_dataconsult Fri, 05/11/2007 - 03:32

Thanks p.bevilacqua,

I tried all the Impedance in the FXO port and I follow the procedure. I notice the clicking noise in some impedance start when the call initiator start talk and in other Impedance the noise clicking start when receiving end start talk.

regard your question about BINA ,I am not from Brazil but I use the BR cpton since it compatible with my PSTN

Paolo Bevilacqua Fri, 05/11/2007 - 03:38


Do you have this noise with the 7920 only, or with other phones types also ? What is the impedance recommended by the thl sweep test?

yhab_dataconsult Fri, 05/11/2007 - 04:16

The clicking noise happens only with the 7920 phons when making call to the PSTN/GSM only.Ther is no any noise happen when making calls to a local ext even for 7920 ext.

about sweept test ,I am not sure what do you mean by this test.

HI everybody, I have the same issue with Cisco 7920 (4.0-03-01)when I receive a call PSTN I hear a crackling noise when the party on the PSTN talks.

On gateway of the CallManager 4.2(3) I?m running a CCME also.

I registered the Cisco 7920 and there is no noise from PSTN CALLS.




yhab_dataconsult Thu, 05/17/2007 - 13:58

I want to add that the click noise hapen only when I talk on the 7920 but ther is no any clicking If I am listen from other side.


is that happen aslo with you.

yhab_dataconsult Thu, 05/17/2007 - 18:48

Yes I just found the soultion,,,

you need to disable the VAD from the dialpeer

[no vad] ,and this only for VOIP dialpeer.

ozgurguler Fri, 05/18/2007 - 04:24

I'm experiencing this problem too. I have "no vad" configuration in dial-peers. It is not the exact solution.

yhab_dataconsult Fri, 05/18/2007 - 15:13


I am very happay since it work with you also

Dear ozgurguler,

actually you will not find VAD in the pots dial peer since this feature work with voip dialpeer only try the below for voip as example:

dial-peer voice 111 voip

no vad

chrismedcalf Mon, 07/23/2007 - 13:39


Just curious: any idea why this (seemingly) only happens with 7920s?


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