Asterisk Setup

Hi All
I have 2 linux system ( in which i have to genrate calls between them ) one with redhat 5 in which i have installed asterisk code . Another one is fedora (Do i have to installed asterisk in that also).
I have one digum card i e TE120P that i have ported into my redhat system. If i want to make a call between 2 system using sip .what should i do
Kindly help