Yealink SIP-T4X Provisioning Manual page 38

Yealink SIP-T4X IP Phones Auto Provisioning Guide
2. Click Autoprovision Now.
The phone will perform the auto provisioning process immediately.
You can activate more than one update mode for auto provisioning. For example, you
can activate the Power On and Repeatedly modes simultaneously, the phone performs
the auto provisioning process when it is powered on and at a specified interval.
The phone will perform the auto provisioning process when receiving a SIP NOTIFY
message which contains the header "Event:check-sync". If the header of the SIP NOTIFY
message contains an additional string "reboot=true", the phone will reboot
immediately and then perform the auto provisioning process. This update mode
requires server support.
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