1 Before You Begin Install the IP Telephony System Make sure you have the following:•IP Telephony System •One or more Internet phones (for example, Linksys SPA-family IP Phones, model number: SPA941)• A router and cable/DSL modem (or gateway)•One or more Ethernet network ...
Phones 1-5 Technology Background 1-6 Session Initiation Protocol 1-6 SPA9000 Media Proxy 1-7 Using the SPA9000 with a Firewall or Router 1-8 SPA400 SIP-PSTN Gateway 1-8 Network Address Translation (NAT) 1-9 NAT Overview 1-9 NAT Types 1-10 Simple Traversal of UDP Through NAT 1-10...