Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Blocked FXO Ports

Hi everybody

I have a CCM 4.2(3)sr3a and many sites with IP telephony. Each site has its Gateway, a Cisco 2811 with FXO cards installed to make and receive calls. The IOS versión of the routers is c2800nm-advipservicesk9-mz.124-3h.bin.

Some of the FXO ports in several sites don't work properly, they block and when a call is received/made in those ports, it gets a silence. when it happends, the "show voice port summary" command shows an status "up down".

I have to restart the port and in the most difficult cases I have to restart the router to get the normal status "up dorm" at the ports if they are idle. The case doesn't seem to be in a particular router, it happens in different ports, in different routers and at different times.

I wonder if it is a bug in the IOS.

Could you please help me with this issue?

this is the relevant configuration of the ports:

voice class custom-cptone DISCONNECT

dualtone disconnect

frequency 421

cadence 200 200

voice-port 0/0/0

supervisory disconnect dualtone mid-call

supervisory custom-cptone DISCONNECT

timeouts call-disconnect 0

timeouts wait-release 1

timing hookflash-out 50

connection plar opx 29035

description CABECERA_PBX

station-id name ENTRADA_1

station-id number 2434928

caller-id enable

and the normal in/out dial-peers

Thanks to everybody



Accepted Solutions
Hall of Fame Super Gold

Re: Blocked FXO Ports

Can you try 12.4(3j) ?

That to align with the latest bug fixes.

Hall of Fame Super Gold

Re: Blocked FXO Ports

Can you try 12.4(3j) ?

That to align with the latest bug fixes.

New Member

Re: Blocked FXO Ports

Hi Paolo

I update the IOS in many of the routers of the network. it seems to be very stable, I think it solved the problem, but I used a newer IOS version: 12.4(19).

thanks for your advice.


Hall of Fame Super Gold

Re: Blocked FXO Ports

Good, thanks for the appreciation and good luck!

Whn you want new features from the router w/ cme 4.2 I can suggest XW7 that is also stable now.