How to connect existing PBX with AsteriskNOW


I’m new to Asterisk and FreePBX, and trying to get familiar with the FreePBX GUI.
I have a PBX with the following specs
OS Version:
Linux IP04 #1 Sat Mar 22 06:53:43 CET 2008 blackfin unknown
Asterisk & GUI Build:
Asterisk 1.4.4
VoIPtel GUI 1.2.6

I recently installed AsteriskNOW into one of my PCs. Is there a way to connect my AsteriskNOW to the old PBX? I would like to work with the FreePBX GUI rather than one currently on my PBX.

I read the following article

Is this the way? or is it a similar method?

Are both boxes on the same network or a vpn between both? An IAX trunk between the two is what you want to do and the link you provided is what you’re after.

Yes, both boxes on the same LAN. Once this is done, do I have to register all my phones to the new server? (For SIP)

No, also make sure you check Intra-Company on your outbound route on both boxes and will maintain your extensions.