[Asterisk-Users] FXS interfaces

[Jerry]

Mike M <no-linux-support at earthlink.net> wrote:
> Think "opposite".  Green modules are fxs and should be handled with the
> fxo signaling. Red modules are fxo and should be handled with fxs
> signaling.
>
> Note the red and green colors here:
> http://www.digium.com/index.php?menu=fxsvfxo

The opposite thing is hard to catch on to at first, but once you
get the hang of it isn't so bad. Plus, the various drivers try to
help out with hints if they think the signalling is wrong.

> _Don't_ plug a phone into a red module jack.
> _Don't_ plug a PSTN line into a green module jack.

Silly question: Can you connect an FXO port to an FXS port? Doing
this for inter-server exchange would be ugly, but I'm thinking that
it might be useful for testing or experimenting. (Maybe not, because
it's not simulating a "true" CO interface, but I was wondering if it
was possible).

As an aside: Why can't you plug a phone into a red module jack? It won't
work, but is there anything harmful there? (Not plugging the PSTN into
the green jacks is obvious -- the ringing voltage on the PSTN will
probably damage the FXS card).

Thanks,
J.