Go to Upgrade - Basic to do web upgrade.
Upgrade: Choose .rom firmware from the PC, then click “Submit” to
start update.
Go to Upgrade - Advanced to configure automatically update
server’s settings.
PNP
Plug and Play, once PNP is enabled, the phone will send SIP
subscription message to PNP server automatically to get auto
provisioning server’s address.
By default, this SIP message is sent to multicast address
224.0.1.75 (PNP server address by standard).