I may not be an expert in this area, but I can provide my perspective.
Outside of the session, you can maintain a separate socket connection with the user and send messages to them when inviting them, triggering a popup similar to an incoming call UI.
@chunsiong.zoom thanks for the response @vic.yang I am currently trying to maintain the websocket and make the tokens available to the users and triggering incoming calls. Looks like there is no recommended signalling by zoom. can you please confirm if maintaining the web socket on my own is the only solution?