Disable BLF on a Cisco SPA Speed Dial Button
Hamshack Hotline has completely disabled Busy Lamp Field because it wastes resources.
VoIP
Grandstream Phones: Specify TFTP Path with Option 66
If you want to specify DHCP option 66 to point your Grandstream phones to a subdirectory on the TFTP server, simply use a value like the following in option 66: ‘192.168.1.1/grandstream’ – note there is no protocol. Only use a protocol for HTTP or HTTPS.