Yealink Auto provisioning User Guide20DHCP OptionsYealink IP phones support obtaining the provisioning server address from DHCP options.You can configure the phone to obtain a provisioning server address from a custom DHCPoption, or the phone will automatically detect the Option 66 or Option 43.To obtain a provisioning server by a custom DHCP option, make sure that the DHCPoption is set properly.To configure the DHCP option via web user interface:1. Click on Upgrade ->Advanced.2. Enter the value (128-254) in the Custom Option field.3. Select the desired type from the pull-down list of Custom Option Type.A valid Custom Option is from 128 to 254. The Custom Option Type must be inaccordance with the one defined in the DHCP server.