Connecting two astrisk server

Hi

I am bit new in Freepbx and wish to understand the process of the connecting two individual freepbx boxes so that user can talk with each other.

Please help its urgent.

Thanks

http://www.cadvision.com/blanchas/Asterisk/IAX2Trunk.html

Depending on your asterisk version, you may need to add requirecalltoken=auto to each side.

It’s a nice guide.