FXO-to-FXO disconnection problem. --- Help me please

[Thotsaphon Lueangwattanaphong]

My environment is as follows :

phoneA--<PBX>-FXO-<Router2821>--WAN--<Router2801>-FXO-<PBX>-phoneB

PhoneA NO# is 375

PhoneB NO# is 312

the related configurations from Router2821 are as follows:

voice-port 1/1/3

supervisory disconnect anytone

cptone TH

timeouts call-disconnect 5

timeouts ringing 10

timeouts wait-release 1

connection plar 614

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

dial-peer voice 8 pots

destination-pattern 379

port 1/1/3

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

the related configurations form Router2801 are as follows:

voice-port 0/0/3

supervisory disconnect anytone

cptone TH

timeouts call-disconnect 5

timeouts ringing 10

timeouts wait-release 1

connection plar 379

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

dial-peer voice 4 pots

destination-pattern 614

port 0/0/3

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

steps to reproduce to problem are as follows:

1. Phone A calls to 379 ( the assigned NO on FXO of 2821 )

the line goes to 614( the assigned NO on FXO of 2801) by plar feature.

2. After got a tone from FXO of 2801, PhoneA dials the NO 312( Phone B NO#)

and then PhoneB starts ringing.

3. While PhoneB is ringing( NoOne accepts the call ) PhoneA hooks-on the Phone.

--- The problem is PhoneB remains ringing.

From the configuration above I apply ringging timeout,disconnect timeout and wait-release timeout

to both routers. But it can't solve the problem

Could anyone help me to solve this issue ?

Thanks a lot.

[dgahm]

Try using connection plar-opx. That will extend the ring to the far side without answering the call.

This doc is mostly about extending hookflash, but also shows plar-opx operation. Not sure if it will work with an FXO to FXO setup, but it's worth a try.

http://www.cisco.com/en/US/tech/tk1077/technologies_configuration_example09186a008009431b.shtml

The OPX mode allows remote users on FXS ports to appear to a central PBX as a directly connected extension. When the FXO port detects a ring signal from the PBX, the router sends a VoIP call setup to the remote FXS port but it does not take the FXO port off-hook. As a result, the PBX only sees the call answer signal when the RemoteSide router FXS port is picked up.

Use the pull down to rate this post if it proves helpful.

Regards, Dave

[PETER NEGUS]

I'm not sure that this is a supported configuration - essentially you are tying two "central office" ports together back-to-back. It is generaly a bad idea to do this - really you should be using 4-wire E&M to do this, or better still BRI or PRI interfaces.

Nevertheless, you may find that configuring both the router and PBX side to Ground Start signalling may overcome the problem, as the problem you describe is a "fault finding classic". See

http://www.cisco.com/en/US/partner/tech/tk652/tk653/technologies_tech_note09186a00800ae2d1.shtml

A debug vpm all should show you what is happening on the interface. It sounds to me as if you are not getting the tone supervisory signals for some reason - in which case moving to ground start may fix your problem. I would also check with the PBX manufacturer the exact signals that the tone supervision uses, as the Cisco locale settings may not match that implemented by the manufacturer.