[cisco-voip] caller-id is audible on fxs

[Wes Sisk]

interesting that there is an audible artifact. the CLID is passed as 2400(?) baud signal from the FXS port or ATA to the analog phone. There were a few ways of doing that. Some of the more common were "type1" and "type2".  I believe the signaling method is also dependent on the cptone as an indication of the geographic region. Is an appropriate cptone selected? You can also configure when CLID is transmitted:
http://www.cisco.com/en/US/docs/ios/12_1t/12_1t3/feature/guide/dt_clid.html#wp1049232

after that it might be helpful to review the output of 'debug vpm signal'. IIRC this shows complete information on what is signaled out of the analog port. It is possible the audible artifact is due to some other feature, such as a misconfigured cptone, rather than being the CLID information.  Generally that is indeed inaudible.

Regards,
Wes

On Jun 1, 2012, at 7:30 AM, chris wrote:

I understand what you're saying the part I guess I don't grasp is if I connect an ATA to the same phone I can get caller id on the phone but even if I pickup before caller-id is sent I do not hear those tones.
I tested on grandstream and linksys ATA's that I had lying around. I'm just trying to understand what the ATA's could be doing differently than the cisco FXS port that makes it work but not audible. I'm not sure if the ATA's are making the volume lower/higher so I'm not hearing it or something like that? I understand the caller id from the trunk to the ATA would use digital signaling through sip but once it gets to the ATA it would be doing the same thing as the cisco's fxs port?

thanks for your help

On Thu, May 31, 2012 at 11:52 PM, Doug McIntyre <merlyn at geeks.org> wrote:
On Thu, May 31, 2012 at 10:43:45PM -0400, chris wrote:
> heres my config id like to have which works but if i pickup before ring 2 i
> hear what i think is the caller-id in the audio

Indeed. That is exactly how CallerID is transmitted on analog POTS
phone lines. Between rings 1 & 2, Bell 202 modem modulation transmits
the the 10 digit calling number and possibly the name to the receiving set.

> im kind of baffled by this and feel like im missing something obvious.....
> i mean the feature works but why in the world do i hear it?

Why wouldn't you hear it? It is analog FSK tones? There's not a lot of
options for signalling on analog POTS trunks. Thats one indirect
reason so many other ways have been designed ties and trunks.

> is there some way i can adjust it to not be audible or change caller-id to
> be send before first ring or something like that? anything that keeps it
> working but not audible would work.....

Use digital stations?  You must be real quick on the answer, as there
are zillions of analog POTS users using landlines with the same thing
and nobody is usually quick enough to answer the phone after ring 1 to hear it.

Otherwise, it is what it is. There isn't any change that can be done
to the caller ID protocol over analog lines after all these years..

With the VoIP phone, you'll get the info transmitted out-of-band.


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