We suppose that you already installed Asterisk and registered the extensions and users we did or similar.

To register a SIP user go to Settings (the last button in the 1,2,3 row) in Menu choose Identity as shown bellow. You scroll the menu by clicking the up or down arrow at the bottom of the display.

If you want to register new user go to Register User and if you want to edit already existing user choose Edit Users

Then type the user @ asterisk ip address i.e. ivan@10.3.3.25. Your asterisk IP address will be different.

After the user is registered the telephone looks like the one bellow.

And now you can dial anybody from the context by just entering the number you want to dial.