private void UpdateCommandStates()
{
((DelegateCommand)AudioCallCommand).RaiseCanExecuteChanged();
((DelegateCommand)VideoCallCommand).RaiseCanExecuteChanged();
((DelegateCommand)AnswerCommand).RaiseCanExecuteChanged();
((DelegateCommand)HangupCommand).RaiseCanExecuteChanged();
((DelegateCommand)RejectCommand).RaiseCanExecuteChanged();
((DelegateCommand)MuteMicrophoneCommand).RaiseCanExecuteChanged();
((DelegateCommand)UnMuteMicrophoneCommand).RaiseCanExecuteChanged();
((DelegateCommand)SwitchVideoCommand).RaiseCanExecuteChanged();
}