*NOW with analog phones

I am setting up analog phone with *NOW in my house. I am abit lose on where to start from all i know is i need an ATA (Analog Telephone Adapters). I am able set up users to talk to each other using softphone on their PC. Below is the settings:

*NOW server :
User A :
User B :
User C : Using analog phone

I am trying to setup User C to talk with User A/B. What is the solution for me to make it possible? Please advise thank you

I also would like to ask if it is possible to connect an analog phone on User A/B PC for them to talk. (reason is some user are not use to using softphone).

For UserC you will need an ATA with 1 FXS port. The ATA registers to Asterisk just like a SIP phone so will require the applicable sip.conf entries.

If the other users want to talk on a regular phone instead of a headset connected to the PC, look into using regular SIP phones. For a little more than the price of an ATA and an analog phone, you can get a SIP phone and not deal with the conversion.