okay just to get this straight. if i have about 20 ppl i wanna get hooked into my asterisk box, do i need 20 telephony adapters to change 20 analog phones to ip phones?
If your ppl are going to use analog phones then you’ll need either 20 ATA (telephony adapter) or you can buy Digium card with 20 FXS port for example, there is also a bunch of other possibilities but those 2 are just the most popular one.
the easiest way in my opinion is to provide your ppl with 20 IP phones. 