Aastra 53i IP Phone - Ending Calls

Model 53i IP Phone User Guide 93
Handling Calls
Ending Calls
To end a call, you first need to connect or reconnect to the call if not already connected
(for example, if your caller is on hold). Press or the line/call appearance
button of the active call to end the call. If connected through the handset, you can also
place the handset back on hook to end the call.
IP Phone UI