We will be implementing Cisco routers for all our VoIP installations. The setup is with a Hosted softPBX outside the organization. Previously we had to research the organizations existing firewall box to see if it was cabable of handling the NAT process for VoIP phones. Now we want to use the existing firewall security capabilities of Cisco 800, 1800, and 2800 series routers to handle this NAT process for VoIP calls.
1. What is this "NAT" functionality that handles VoIP calls outside the organization (though a firewall) called? I don't believe it's NAT(something about packet rewrite and handling support of codecs like G.711).
2. Do all these series routers firewallls handle this process and how is it implemented?
3. Any resources you could point me to in learning about this process would also be appreciated.