A bridged appearance button shows the state of one of another user's call appearance buttons. It can be used to answer or join calls on that other user's call appearance button. It can also be used to make a call that the call appearance user can then join or retrieve from hold.

When the user's call appearance button alerts, your matching bridged appearance button also alerts. The bridged appearance button can be used to answer the call on the call appearance button user's behalf.
When the call appearance button user answers or makes a call using that call appearance, your matching bridged appearance button shows the status of that call, for example connected, on hold, etc. The bridged appearance button can be used to retrieve the call if on hold or to join the call if active.
Bridged appearance buttons are not supported between users on different systems in a SCN.