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CallManager - IP Phone non stop ringing

Unanswered Question
Oct 1st, 2002
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IP Phone non-stop ringing after PSTN caller disconnect the line.PSTN caller call to IP phone thru H323 gateway FXO port, gateway pass to CM, did not pick up the call, caller disconnect the call, IP phone still ring. there is no problem gateway pass to analog phone attached to FXS port


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marinaibm Wed, 10/02/2002 - 00:27
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When loop-starting signaling is used, a router's FXO interface looks like a phone to the PSTN switch. The FXO interface will close the loop to indicate off-hook. The switch always provides a battery so there is no disconnect supervision from the switch side. Since a switch would expect a phone user (example of an FXO interface) to hang up the phone when the call is terminated (on either side), it also expects the FXO port on the router to hang-up. This "human intervention" is not built into the router. The FXO port expects the switch to tell it when to hang-up (or remove the battery to indicate on-hook). Because of this, there is no guarantee that a near-end or far-end FXO port will disconnect the call once either end of the call has hung-up.


paul.harrison Wed, 10/02/2002 - 07:13
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You need to configure the port as plar-OPX, otherwise what you are getting is normal.

The router is answering the call and then telling call manager that there is an incoming call, however it relies on the call manager to then tell it that the call has ended, which it can not do.

If you configure the port as plar-OPX then the router signals a new incoming call to call manager but does not answer it until the extension picks up, it can then clear down.

have a look at




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