[asterisk-users] Astribank loop current adjustment

[Tzafrir Cohen]

On Thu, Oct 23, 2008 at 02:50:05PM +0200, Udo Schacht-Wiegand wrote:
> For a door opener on an Astribank FXS port we need a loop current of 24.5mA .
> It does not function with the Astribank now, the dialtone becomes quiet 
> immediately after pressing the button on that device.
> I've seen a limit of 23mA in the zaptel source.
> Is it possible to change the loop current of the Astribank somehow?

A phone that is on-hook is supposed to be an "open circuit" and ideally
not draw any current. In the real world this doesn't really happen. The
Astribank detects this by setting two limits. Anything above the high
limit is considered "closed circuit" (off-hook). Anything below the
lower limit is considered "open circuit" (on-hook). 

The values of those limits are 6.72mA (low) and 10.16mA (high). Thus
24.5mA is well into what is considered an "open circuit". If you try to 
raise those limits, you may encounter problems with detecting a phone 
being picked up and such.

As Steve mentioned, tweaking this can be done by setting registers.
However those tweaks tend to interact with other things in strange ways.
Therefore I would not provide here the specific details without fully
understanding the situation. Generally for such matters contact
support at xorcom.com .

-- 
               Tzafrir Cohen
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http://www.xorcom.com  iax:guest at local.xorcom.com/tzafrir