Disconnect own station from ongoing group call feature

Feature:	Disconnect own station from ongoing group call
Default directory number:	7884
Feature number:	53
Parameter 1:	0
Description:	Dialling 7884 or pressing C-key during groupcall reception will disconnect the groupcall audio in the station. Additional notes: The station will not be free to receive a new groupcall before the first groupcall is disconnected totally. EVENT/RCO control is not turned off before the groupcall is disconnected totally. C-press in Idle disconnects ongoing groupcall if this feature is included in the Class of service for this station. (C-press in conversation just disconnects the conversation as before). Disconnect-from-groupcall is also available as a data protocol message ST GROUP DISCON. See also Next Group Call