I've completely forgotten where I used to get this.
I remember getting a list of all hotdesk users together with the handsets they had logged into.
I can't figure out where I used to get that from.....
The scenario is I can see somebody trying to hotdesk logon, but they are clearly putting in their PIN instead of the extension number. I suppose they will eventually log a ticket, but If I can just find out who it is by looking at which extension was logged onto that base handset last, I could fix it up using the MitaiBrowser tool.