The Linksys/Sipura by default gets it's IP address from the DHCP function of the router it is connected to.

For the Sipura SPA-1000, SPA-1001, SPA-2000, SPA-2002, and SPA3000 the IP address of the device can be found by lifting the handset attached to any Line port and dialing ****, followed by 110#.

The SPA-2100, SPA2102, and SPA3102 is a router and has two IP addresses - 1 external and 1 internal. The internal IP address has a factory default address of 192.168.0.1. The external address can be found by dialing ****, followed by 110#.

For the SPA-841 press the settings button at the bottom right corner of the telephone (marked with i), scroll down to the 9 Network item on the menu and press the select soft key.

For the SPA921, SPA922, SPA941, and SPA942 press the settings button (marked with a square with a folded corner), scroll down to the 9 Network item on the menu and press the select soft key.