We have Time Warner Digital Phone, and would like to hook it into an Asterisk system. Should I buy a Sipura adapter? Do I need one with an FXS and FXO port, or will just FXS do? The Time Warner Digital Phone system plugs into a wall jack, and all our other phones get a dialtone.
You need an FXO adapter to plug into your Time Warner box. FXO cards/devices act like a phone, listening for a ring, pick up use the dialtone, etc. FXS devices act like the phone company - generating the ring, making a dialtone, etc.
SO, if you were to use your Time Warner line, you could get an FXO/FXS device, and it would be in-line with your home phones. FXO port plugs into Time Warner box, Asterisk does it’s magic with the device, then if it needs to, sends a ring on the FXS port, which is plugged into your house to ring your phones.