Yealink SIP-T2xP Auto Provisioning Manual page 62

Yealink IP Phones Auto provisioning Guide
You can add the option 66 via DHCP Turbo. The following shows the detailed processes.
1. Click Named Policies-->Global, right click the blank area on the right of the main
page and then select New Option.
2. Select TFTP Options from the pull-down list of Filter.
3. Scroll down and double click MS option 66.
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