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Problem with Analog phones/FXS ports?

Unanswered Question
Apr 13th, 2012
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I have a Cisco 3825 with a high-density voice module


Some of the phones that hang off this card can make calls, but will not ring when called: I can actually feel the hammer in the analog phone trying to ring, but it never hits the bell. Looks like it might be a voltage issue


The ports are configured thus:


voice-port 1/0/17

timeouts initial 60

timeouts interdigit 60

timeouts ringing infinity


dial-peer voice 5220 pots

destination-pattern 5220

port 1/0/17


Looking at the output when the phone is called:


1/0/18         --  fxs-ls      up    up   on-hook  ringing  y


The analog phone is 400-500 feet away from the router


Does this look like a voltage problem?


Is there something I can do in the router to up the voltage?

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Gajanan Pande Fri, 04/13/2012 - 10:20
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Colin,


I dont remember the allowed cable length connecting the analog phone from FXS port of router but to quickly eliminate cable length issue, would you be able to take an analog phone & connect it locally on the router's FXS port to see it makes a difference ?


GP.

paolo bevilacqua Fri, 04/13/2012 - 10:27
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Beside loop length, have you measured resistance? And ground isolation ? Have you tried electronic ringer phones or only mechanical ?

There is nothing that can be done on router to increase ring current, beside hardware remedies.

Colin Higgins Fri, 04/13/2012 - 10:50
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I haven't tried an electronic ringer, nor have I measured resistance (I wouldn't even know how to go about doing that--I would imagine it requires an advanced cable tester)

paolo bevilacqua Fri, 04/13/2012 - 11:09
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No it only requires a $5 multimeter.

Try a different phone.

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