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New Member

MGCP- FXO disconnect

Cisco 3745 Router connected with FXO Port.

When call is made from PSTN phone ir rings the IP Phone in the setup. If the PSTN user disconnects the call, without the call being answered, at the router end and the IP Phone, the call is not showing disconnected. The IP PHone keeps on ringing continuosuly.

CCM - 3.3.

Router IOS -123-1

Tried the option of using superviosry disconnect forcing the port to detect that the call is disconnected. Even this has not helped.

Any othe parameters to ensure that call is disconnected properly.


Sundara Rajan.R

Cisco Employee

Re: MGCP- FXO disconnect

This is an inherent issue with FXO ports.

Here is the page that describes what happens:

You need to know whether you will get power denial and or what tone you want to disconnect on and the cptone must be set correctly for the country where this is.

Here is more information about the feature:

Hope this helps.

New Member

Re: MGCP- FXO disconnect

I have the same Problems with CCM 3.3(3) and 3725 (2.2(15)ZJ3).

All work well if my Router is on SRST status.

voice-port 2/0/0

echo-cancel coverage 24

cptone CH

timeouts call-disconnect 5

timeouts wait-release 5

timing hookflash-out 50

connection plar opx 540

supervisory disconnect anytone

New Member

Re: MGCP- FXO disconnect

I found into Cisco IPTT v2.0 training Documentation this phrase:

MGCP gateways can support several interfaces to the PSTN, and most PSTN interfaces provide end-user release disconnect supervision, Only FXO (loop-start) interfaces lack this ability.

It’s that true?

How can I solve the problem, should I configure the Router with H323 or it exist other solution?

Cisco Employee

Re: MGCP- FXO disconnect

This is quite true, it is one of the main reasons to think twice about using FXO. Here is more info and possible workarounds:

A feature was introduced: "FXO Answer and Disconnect Supervision" to try and workaround this shortcoming:

Hope this helps...

New Member

Re: MGCP- FXO disconnect

I have two other questions.

1. The FXO Answer and Disconnect Supervision Feature work only on H323?

2. If I have FXO (loop-start), must I forget the MGCP?