[Asterisk-Users] Single FXS port with multiple phones ?

[James Pooton]

Hello all..  

I have what I think is a rather simple question here.  We're using * for
home and business lines with great success so far. (inbound, outbound,
several hard phones, voicemail, IVR, etc)  

My next project is to get some of my traditional POTS phones at home on the
system.  I understand this requires an FXS interface(s), which really is my
question.  If I don't care about having individual extensions for every line
(as most "homes" don't) then I'm thinking it should be possible to just have
a single FXS interface that would replace the telco's normal line connection
to my home wiring after the demarc (assuming it could provide the juice
required by my phones).  Stop me here if I'm wrong. :)  

In trying to research this further, I'm looking at getting an SPA-3000 to do
the FXS duties (as I could also use the FXO interface for something else),
and it gives a variety of FXS specs.  After a bunch of Googling it would
seem that REN (ringer equivalence number) is one I need to pay attention to.
The SPA-3000 says it can provide 3 REN.  So as long as I stay under that
total for my phones am I pretty much safe or are there other specs that I'm
overlooking?  Like possibly if more then one phone is off hook to talk on
the line at the same time?

In a semi-related question, I have a bunch of 2.4 Ghz cordless sets here and
the base stations say "Ring Equivalence: 0.0B".  Could this truly be the
case?  Like the phones just monitor the line for a ring signal but don't
draw current from it when it's ringing. I can see how it's possible as they
have their own AC, but I just wanted to confirm.

Sorry for the long post, I thought it would be shorter.

-James