Basic AsteriskNOW setting with FreePBX

Hello there,
I am pretty new in both asterisk&FreePBX. And I am trying to do a basic experiment with asterisk.

I need to install a SIP server, register two IP phones which are in the same network and call each other.
I installed AsteriskNOW 3.0.0 into a PC which is denoted as the SIP server. I did yum update and configured the network settings in order to connect the FreePBX from another PC.
From the FreePBX I updated the modules and then added two extensions which are 1000 and 1001 from Applications -> Extensions.
On the ther hand, the IP phones are set with the extension numbers, userID, secret, and SIP server IP.
Asterisk info says:
Sip Peers:
Online: 0
Online-Unmonitored: 0
Offline: 2
Offline-Unmonitored: 0

I do not know what is wrong but calling each other from one IP phone to the other does not work. I may miss some setting but what I cannot figure it out.

Any help would be greatl appreciated…