Show Phone Screen (Clear screen/Home button)

OpenStage phones aim to be as easy to use as possible but with a high level of functionality and flexibility there can be scenarios, particularly on the low-end models where it is not always so easy to find the way out of a menu structure. Also, because OpenStage 15, 20 and 40 do not have a CallView mode key (like OpenStage 60/80 does), there is no easy short-cut back to CallView mode.

A new FPK/FFK feature is introduced that provides this simple shortcut directly to Callview mode. Pressing such a programmed FPK/FFK is the OpenStage 40/20/15 equivalent of pressing a dedicated CallView mode key (which OpenStage 40/20/15 does not have). The switch to Callview is immediate and will always happen when the key is pressed unless the phone is in a blocking state (e.g. waiting for the user to press an FPK to be programmed).

The default label for the new FPK feature is Phone but the user can change this if they prefer another term.

The Phone FPK/FFK feature will not make use of any LED associated with the FPK/FFK on which it has been programmed. However, when the Phone key is used to change to Callview mode, the LEDs in the mode keys on the OpenStage 40/20/15 will correctly indicate the switch away from the current mode to Callview mode.

The Phone key will perform no actions other than:
 * 1) the switch to Callview mode.
 * 2) the toggling between Lineview and Overview screens once in Callview mode on a multiline/keyset OpenStage 40.

Pressing the Phone FPK/FFK while the phone is already in Callview mode will have no effect unless it is a multiline/keyset OpenStage 40.

The Phone key:
 * 1) will not introduce any new behaviour in terms of cancelling or aborting actions that may be in progress when the key is pressed. So, it the act of switching to Callview (using the existing method of pressing mode keys) currently has the side-effect of dismissing pop-ups or context menus, the same behaviour will occur when the switch to Callview is triggered by pressing the Phone key.
 * 2) will not answer an alerting/ringing call.
 * 3) will not select an outgoing line and/or display a dialler.
 * 4) will not dismiss any dialler or other kind of popup currently showing in Callview.
 * 5) will not cause any interactions with call-related features e.g. retrieve a call from hold.
 * 6) will not make a call to a currently highlighted entry (e.g. Phonebook entry) as part of the switch to Callview.

OpenStage 20 will only support programming of the Phone feature onto an FFK.