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1. Login webpage, and click Account-> Basic: Shared Line=SCA
2. Click Function Keys->Line key:There must be a line key to bind the target account here.

3. In Endpoints Admin UI:

   (1)Go to Configuration > Device Definitions

   (2)Edit the Device Definition of an HTEK phone

   (3)Set "SLA Support" to Yes

Q3: Why phone doesn’t reboot when recieve check-sync message?

Please check the Setting:

Login webpage, and click Setting→Preference→Check-sync reboot=Enable