In your Router select DHCP Server tab > select go to TFTP/FTP Server Name (option 66): and put in the following text

ftp://:@sip@#$%^&* >  ( note: do not use the symbols, but do use the : colon and // as indicated.)

Both values and will be found on the Settings>Service Settings screen under Provisioning Server Info.

With option 66 being used in this fashion you do not need to provision the phones they will go out and get their config as long as the extension(s) are built in the portal.  

Note:    Please make sure that the phones are set to use "option66" as the boot server.