Manually reset FXO port

Unanswered Question
May 7th, 2007

How do you reset an FXO port?

I have this problem too.
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Paolo Bevilacqua Mon, 05/07/2007 - 15:04

In theory, shut / no shut in voice-port configuration mode.

Unfortunately there are certain "conditions", I would call these bugs, in which no maneuvering has effect, and the port is just stuck until the router is reloaded.

FXO are the most subject to these problems.

Hope this helps, please rate post if it does!

wilson_1234_2 Tue, 05/08/2007 - 04:09

We have a B1 line that rings once and then goes to dial tone.

I have reset the FXO port and reloaded the router.

What could I look for to isolate if this is a line problem or our equipment?

Paolo Bevilacqua Tue, 05/08/2007 - 05:08

Excuse me, what is a B1 line ?

What means, rings once then goes to dial-tone ?

Router configuration ? IOS used ?

wilson_1234_2 Tue, 05/08/2007 - 05:28

A regular POTS line into the building that is using the FXO port?

when dialing the device that is on the remote site router FXO port, it rings once then you hear that it has picked up, it then goes to dial tone.

The router is a 2811, 12.4(9)

I can see the port go off hook when doing a "sh voice port sum"

I am not familiar with troubleshooting voice, I was just looking for some tips on what to look for

b-chernish Thu, 05/17/2007 - 06:43

Have you resolved this issue? If not I would suggest looking into the router configuration. In addition to the voice-port configuration, you will also need a corosponding "dial-peer". I have seen situations when incomplete dial-peers are in the config ahead of the correctly configured dial-peer. When that happened I got the same symptoms -- one ring and then dial-tone.


rob.huffman Tue, 05/08/2007 - 06:05

Hi Wilson,

Just to add a note to Paolo's good info. The first thing to do is to isolate the Line from the equipment. Connect an Analog phone to the Line before it attaches to the equipment and see if the problem still exists. If yes/ then contact Telco provider (may be a problem often referred to a Ring-Trip), if No/ reconnect the Line and continue troubleshooting.

Let us know,

Hope this helps!


wilson_1234_2 Tue, 05/08/2007 - 06:37

Thanks for the reply,

Is an FXO port then a port that will take regular POTS telephone signal and route it to an end device?

rob.huffman Tue, 05/08/2007 - 10:14

Hi Wilson,

Yes, that is a reasonable description. Here is another one (along with some other good info);

The Cisco Foreign Exchange Office (FXO) interface is an RJ-11 connector that allows an analog connection to be directed at the public switched telephone network's (PSTN's) central office or to a station interface on a private branch exchange (PBX). The FXO sits on the switch end of the connection. It plugs directly into the line side of the switch so the switch thinks the FXO interface is a telephone.

From this good doc;

Understanding Foreign Exchange Office (FXO) Voice Interface Cards

Hope this helps!



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