My router doesn't have option 66 available. How can I auto provision the phones with it?
You can add the auto provisioning URL directly into the handsets. http://p.sipvoice.com.au
Determine the IP address of the handset by pressing the OK button ONCE. Note this IPv4 address (example 192.168.0.30)
Open a web browser and enter this IP Address into the address bar

Login to the handset (there could be two different log in to check :
Username : admin
Password : admin
or
Username : admin
Password : flex
Settings --> Auto provision
Change the Server URL - http://p.sipvoice.com.au/
Click Autoprovision Now at the bottom of the page.