SPLIT 2 cards for 2 computers using only 1 as 'SERVER'

I’m quite an asterisk newbie and have a question about my desired config:

1.) Main box, with 1 FXO card, will be the asterisk server
2.) A Desktop box with 1 FXO card, will work as a “slave”

Why do I have this config? Simply put, I have 2 Ambient PCI cards (how difficult it is to find old compatible cards!), and new boards lack a good number of good old PCI slots, so I have to split one for each box.

My setup idea is to use 2 PSTN lines, one with a cheap plan for incoming calls (private number ) and another one I can use without being charged in a per-minute basis for outgoing calls. So I need each of the boxes to use one PSTN line.

My question is: what exactly do I need to get this setup working (if possible). I believe it will be much like using an FXO gateway appliance.
The question is: how do I config the desktop box to publish its device to the real server, so that it will act like an FXO appliance to the server?

I’m not a linux/computer newbie, just an asterisk newbie, all I need is some pointers to the right pieces of documentation; I’ll take care of the rest… and eventually post new reply here just in case I found myself in trouble :smiley: