Make Free Calls On Your iPhone with Asterisk and Fring

You enter the extension you set up earlier in the "User ID" field. You enter the password you assigned to the extension in the "Password" field. And you enter the DNS name for your Asterisk server in the "Proxy" field. Tap on "Login" and Fring will register the extension with your Asterisk server and you're ready to begin making calls and enjoying your new WiFi SIP phone.