DHCP Options

Phones fetch their provisioning files from the IP address specified in tftp-server-name. Example below is for ISC DHCP.

subnet netmask { authoritative; range; option routers; option broadcast-address; option tftp-server-name ""; option ntp-servers; }
An alternative to tftp-server-name is the proprietary option 150 which allows for a list of IP addresses to be specified.

option tftp-servers code 150 = ip-address; subnet netmask { ... option tftp-servers,; }