Philips V24CT User's Reference Manual page 156

Extended Overview (CMS only)
Note—
gateway is inoperational, the message "SDN comm error - inter-network
gateway failed" will be displayed in the message area of the main screen
display. The Alert Notification display is removed if
pressed on the source bedside monitor or
station. All ***-star, **-star and hard INOP alerts will generate alert
notification.
4-18 Other Patients
If the gateway is configured to provide Alert Notification and the
Silence/Reset
on the central
Silence
is