The check-sync mechanism allows the initiation of a profile (configuration file) download from remote.

A SIP NOTIFY has to be used for sending the check-sync command. As additional information the protocol includes the switch, if a reboot has to take place (some operating systems need a reboot to make the new settings valid).

The following pictures show the principle of this.

Notify message without a reboot:

NOTIFY sip:1018@192.168.2.198:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.2.210:41008;branch=z9hG4bK.47c21b3d;rport;alias
From: sip:unknown@192.168.2.210
To: sip:1018@192.168.2.198
Call-ID: 1234@192.168.2.210
Event: check-sync;reboot=false

Notify message with a reboot:

NOTIFY sip:1018@192.168.2.198:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.2.210:41008;branch=z9hG4bK.47c21b3d;rport;alias
From: sip:unknown@192.168.2.210
To: sip:1018@192.168.2.198
Call-ID: 1234@192.168.2.210
Event: check-sync;reboot=true

SIP NOTIFY has also other options like RE-Registration / factory-reset see: Trigger the phone to reset or synchronize its settings via provisioning