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

Intermittent POTS Lines - System Not Answering

Cisco 2800 Series with 10 POTS Lines connected to FXO Ports on the router.

Intermittently calls are coming in but the line rings & rings & rings.

POTS lines connected via Verizon to a main number hunt group. Verizon tested hunt group & lines no problems.

Listed below my "voice-port" config.

Do I need to add anything to "reset" the lines.

voice-port 0/0/1

translation-profile outgoing SRST

ring number 2

no vad

no comfort-noise

timing hookflash-out 500

timing inter-digit 50

connection plar opx 6201

station-id name line 2

station-id number 6201

caller-id enable

dial-peer voice 1 pots

destination-pattern ...........

port 0/0/0


Thanks in Advance !

New Member

Re: Intermittent POTS Lines - System Not Answering

I don't know if you are seeing the same issue, but there is a known bug (CSCsc11833) in Cisco 12.4 IOS that causes analog trunk lines to seize and the only workaround is to reload the router. The problem re-occurs anywhere from 5 minutes to a couple of days after a reload.

We have a 2821 router with EVM module, DID/FXS and FXO ports and have seen the problem with both the DID and FXO ports. Running the latest 12.4 IOS. Cisco TAC case still open on it.

Good luck,



Re: Intermittent POTS Lines - System Not Answering

You may just have one line with a bad cross connect between the telco demarc and router. Do a show voice call summary continuously as you dial in to see if you have one port that never sees ring. This will also tell you if you have a bad port that sees the ring but doesn't answer. If you find a suspect bad line put an analog phone on it and call that number.

A debug vpm signal will also show ring, but if the lines are busy it may give you too much output.

Rate this post if it helps.

CreatePlease to create content