Routing between two nic on centos

I have a PBX box with freepbx on asterisk with two nic

nic1
-Connected to local network and phones
-IP 192.168.2.200
-gateway 192.168.2.1

nic2
-connnected to sip gateway
-ip 172.29.10.10
-gateway 172.29.10.11

sipserver address 10.100.100.100

how do I do the routing
I am newbie in linux
Please help!!