[Asterisk-Users] FXS interfaces

[Mike M]

On Wed, Jun 22, 2005 at 02:58:54PM -0400, Jerry wrote:
> 
> 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.

commheads should be accustomed to this sort of thing.  DTE/DCE is an old
one that is similar.  Become one with the confusion.
> 
> > _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).

You try it first :-).  Sounds logical.
> 
> 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).

Yeah.  I thought about that too.  I decided it was just good policy to
use the rules above.

Here's another question:  If you plug the PSTN wire into a green module
is there a fire risk?  I don't know if the Digium equipment has CE/UL
ratings.  If they don't then it may be worth elevating caution to
concern for fire safety.

-- 
Mike
> 
> Thanks,
> J.
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