FXO Ports Lit With No Active Calls

Unanswered Question

We have a customer with a UC500 with an addon 4 port FXO card.  Two times in the last couple of weeks, 6 of 8 ports were lit up with no active calls.  There are 5 FXO lines plugged in so one of the lit ports does not even have a cable attached.  I rebooted the box to get it to work again.

What kind of troubleshooting could I do on something like this?

Thanks in advance for any help.

I have this problem too.
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David Trad Wed, 07/22/2009 - 16:23

Hi jcarter,

What kind of troubleshooting could I do on something like this?

Shut down the ports that are not being used by config terminal, just do a shut on the port ID.

Then i would look at the following:

1. Are you Call forwarding from one PSTN line (Incoming) to another PSTN line (Outgoing) ?

2. Are you bridging two PSTN lines for maybe SNR?

3. Is it only ever one port light or two port lights at any given time?

I raise the above as there is a known problem that haunts me all the time, that is the locking up of PSTN lines when bridging two lines together, mostlyt his problem is seen in the Points 1-2 scenarios, you can see the port lights being on allthough there are no calls active on the system.

We highly recommend to all clients now not to do PSTN bridging, actually we now try and get the majority of our clients onto outbound SIP trunks, this is one good way of beating this issue, and it can also reduce their oeprational telephony costs.

I note that this problem is mostly identifiable on IP-PBX systems, i dont actually recal ever seeing this problems on old Key based system, but i know Cisco are not the only IP-PBX company to have this problems, other systems like * have found work arounds, but even they are not solid and tend to be a hit and miss.

I hope this is not the problem you are experiencing, as i can tell you there is no sure fire way of getting rid of this problem other then going to ISDN or SIP trunks.

Cheers,

David.

I appreciate the feedback.

The 2  scenarios do not apply for my situation.

When they called me, 6 ports were lit at the same time.  I have not dropped in when they were not having problems to see what it looks like.  It might start off with 1 lit then 2 then 3 etc until all the FXO ports are disabled.

There is one thing I realized while reading the FXO disconnect documentation.   When I originally did the install, the auto attendant was not working correctly.  I added the no battery reversal line to the voice-port lines.  The auto attendant problem was fixed but maybe it created this new problem.

David Trad Wed, 07/22/2009 - 18:11

Hi jcarter,

I see what your saying :)

OK can you please post the voice-port configs then, it would be good to see what you have there.

Cheers,

David.

Here is what the voice ports look like:

voice-port 0/1/0
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4FXO-0/1/0-Custom-AA
caller-id enable
!
voice-port 0/1/1
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/1/1-Custom-AA
caller-id enable
!
voice-port 0/1/2
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/1/2-Custom-AA
caller-id enable
!
voice-port 0/1/3
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/1/3-Custom-AA
caller-id enable
!
voice-port 0/2/0
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/2/0-Custom-AA
caller-id enable
!
voice-port 0/2/1
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/2/1-Custom-AA
caller-id enable
!
voice-port 0/2/2
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/2/2-Custom-AA
caller-id enable
!
voice-port 0/2/3
trunk-group ALL_FXO 64
translation-profile incoming CID_ADD9
no battery-reversal
connection plar opx 290
description Configured by CCA 4 FXO-0/2/3-Custom-AA
caller-id enable
!

David Trad Thu, 07/23/2009 - 21:28

Hi [email protected],


Can i suggestion you apply the following config to your Voice Ports please:

voice-port 0/1/0
trunk-group ALL_FXO 64
supervisory disconnect dualtone mid-call
compand-type a-law (Or u-law what ever you use in your region)
translation-profile incoming CID_ADD9
timeouts call-disconnect 3
timeouts wait-release 3
no battery-reversal
connection plar opx immediate 290
description Configured by CCA 4FXO-0/1/0-Custom-AA
caller-id enable

This is a standard config i use, if CCA does not enter it in allways modify it manually myself, this is the only way i can get PSTN lines to work properly.

Also i would suggest you remove the battery-reversal command whilst testing this config setup, your AA should work without it there.

It is safe to say you can apply the above config to all your voice ports if you want too.

Note: the connection plar opx immediate 290 can be put back to normal I.E remove the immediate command, this only effects the caller-id it will not display it as soon as the phone rings as the system wont capture it till sometime after the first ring, it is not normal operation for the CID to be broadcast at the same time as the first ring.

Cheers,

David.

I am trying the config you suggested on the FXO ports.

While I was at the site, I checked the cables plugged into the FXO ports.  There was a mixture of straight-thru and crossover.  The crossover ones need the no battery reveral command.  The straight-thru ones do not.  I am going to change them over to all straight-thru.


Thanks again for the help.

This site is great because everyone shares their experience with other members.  I hope some day to have enough knowledge to help other people out with their problems.

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