A host notification tells an employee their guest has arrived. It fires the moment the visitor checks in, usually by email, SMS, Slack or Teams, and removes the need for a receptionist to find the host manually.
It is the feature that decides whether a reception desk needs to be staffed at all. If arrival alerts reach hosts reliably, a small office can run an unstaffed lobby with a visitor badge printer and a tablet.
Look for escalation. If the host does not respond within a few minutes, a good system notifies a backup or a team channel, so a visitor is not left standing in a lobby.