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FXO Disconnect Problem - 1750

After I place a call from an FXO port (connected to the PBX), the port never more disconnect, even with both sides on-hook. The call originates on the FXO port, coming from the PBX. The FXO port is in a 1750 with 12.2(8)T.

The other side is an E1 gateway (5350).

Could anybody help on this?

Thank you,


Cisco Employee

Re: FXO Disconnect Problem - 1750

FXO disconnect supervision can be problematical.

When loop-start signaling is used, a router’s FXO interface looks like a

phone to the switch (PBX, PSTN, Key-System) it is

connecting to. The FXO interface will close the loop to indicate off-hook.

The switch always provides battery, so there is no

disconnect supervision from the switch side. Since a switch would expect a

phone user (which an FXO interface looks like) 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 battery

to indicate on-hook). Because of this, we cannot guarantee that a near end

or far end FXO port will disconnect the call once

either end of the call has hung up.

Check out this link for possible solutions:

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