FXO finding if line is plugged in

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May 5th, 2009
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Is there a way on a VIC FXO to find out if there is an actual line plugged in to it?

I know on a Linksys Gateway SPA400 the minute you plug the line in, the voltage indicator will change; which indicates that it's actually plugged into something. Is there a similar info on a Cisco FXO or something similar?


Thanks.

Cisco Endorsed by Jose Carlos Zamora Araya
paolo bevilacqua about 8 years 3 weeks ago

Not really. You can attempt a call with csim start and on a disconnected port you you see lack of current loop when off-hook, with "debug vpm signal"

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paolo bevilacqua Tue, 05/05/2009 - 14:15
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Not really. You can attempt a call with csim start and on a disconnected port you you see lack of current loop when off-hook, with "debug vpm signal"

kherzog Mon, 08/03/2009 - 19:26
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On the ISR router with a FXO port you can also use a command to verify voltage for the voice port. There is a Cisco document that details the command used below, it will report if there is any voltage on the fxo port in question. I used this command to remotely troubleshoot an outage report for an overhead paging system. The paging system is providing the voltage/battery. If this was a CO type line, then, again the PSTN is providing the battery, so if it is connected to the fxo, you must have voltage.

Example:

> term mon

> test voice port port# si-reg-read 29 1

>

> A value of 0x00 indicates there is no voltage being seen on the line/voice port.

> You need the terminal monitor command to see the output of this command on the screen.



homegw-220#ter mon

homegw-220#test voice port 3/0/2 si-reg-read ?

<0-200> Starting register in decimal: 0 - 200


homegw-220#test voice port 3/0/2 si-reg-read 29 ?

<1-6> Number of registers to be Read: 1 - 6


homegw-220#test voice port 3/0/2 si-reg-read 29 1

homegw-220#

Jun 18 2009 16:44:53.629 EDT:

Values read from SiLabs Codec connected to DSP 0, channel 2:

--------------------------------------------------------------

Register 29 = 0x00


Jun 18 2009 16:44:53.629 EDT: >


A value of 0x00 indicates there is no voltage being seen on the line/voice port.


paolo bevilacqua Tue, 08/04/2009 - 03:35
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To the person that rated my post an "1":


you're misusing the rating system, because the information that I gave is correct to the best of my knowledge, and given in good will.

Robert Dantes Fri, 10/25/2013 - 16:27
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I know this thread is kinda old but incase anyone passes by this thread looking for an answer to the same question as the original poster.


test voice port x/x/x   si-reg-read 29 1

This command can help in detecting if the line connected to the port has a current; Need to look for anything not 0x00. since 0x00 means no electric current

Robert Thomas Fri, 10/25/2013 - 21:04
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Although relatively simple I use a "show voice port summary" and then call into the FXO line. You will see the port chaning status to ring-detected, if the status show no change, then there's nothing connected.

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