Going to voip piece mill

I have ATT t3 with “voip card” in the router to provide analog tone to my old pbx. I assume this voip card is an fxo?

I would like to continue this same line set up for now but to get rid of the old pbx and use voip end points instead of pbx phones.

I know I will need a FXO card in the asterisk server. My question is that since I already have voip card in the t3 router is there a problem pluging those into an fxo card in the asterisk server?

At some point in the future I will do away with the voip to analog setup on the router and go full voip all the way, but I’d like to have the internal infrastructure up and running before doing that. Too big of a job for one man to do all at once.


If it’s providing dialtone to a PBX or other device, it’s FXS. On your side, to connect to FXS, you need FXO. So, you’re not wrong there.

You do want to ensure that if you’re installing an FXO interface on the Asterisk side that you’re actually connecting to FXS on the router there. Try plugging in a traditional analog telephone. If you get battery (dialtone’s nice), then it’s FXS on the router and you need FXO (an analog telephone set is an FXO device).


Ah yes fxs on the router to fxo on the pbx server then. Thank you.

Are there any problems/caveats going from Voip to fxs to fxo to voip like Im planning?