HT503 FXO line loops exchange line permanently


Hi All,
my HT503 is looping the exchange line even when showing ‘idle’. When a PSTN number is dialled all you get is the busy signal from the exchange. There is of course no incoming PSTN calls either as line is busy.
The line volts drops from ~48volts when line is not plugged into HT503 to ~30volts when plugged in.
So is this a hardware problem or are there some line settings that I can do to not draw this current and loop the line.


This may depend on a number of various settings none of which we know yet. If the device is new and there was no issue in its setup, then I suggest we give the device the benefit of the doubt as to it being defective and we assume there may be some settings issues.

What the device is connected to in the way of a PBX or other?

How are calls to the FXO port accomplished?
Can you post screen shots of the settings for the various settings pages?


OK first I should state that it used to work but now is giving the problems described.
It is connected to an Asterisk based PABX (PBX for some) the dialplan directs the numbers to the FXO port.
I f tried several resets and also the new firmware just released for good measure no thing has improved.
Dialling the port directly and listening to the dial tone when it is reset is of low level and hummy. DTMF from the dialling phone does not break the dial tone presumably because of the low levels.
The Line indicator on the unit is unlit when the fxo port is not in use (but still loops the line) and lit when in use from the PABX or the phone on the FXS port (dialling direct). When the Line indicator is lit the looped voltage at the port is much lower so its behaving sort of as expected.
But a; the constant looping of the line albeit not by much current is not good
b; low levels and hum when listening on the line, and
c; unable to dial out when dialling the port directly
Leads me to think that this is a hardware problem on the line side of the fxo port.
cheers DM
I guess I get another one and try again.