DND presence state on no subscribers

The purpose of this feature is to reflect the fact that nobody is subscribing to a line on a presence shortcut.

In the version 8.1.xxx or lower, we had the possibility to monitor the fact that no traders are currently subscribing to a line and respond "busy" on each incoming call. But this line is seen in the available state in the presence point of view.

Thanks to this option, when no traders are currently subscribing to the DDI line, this line is seen as busy state in the presence point of view .

Attention points:

•This feature is only available on Cisco CuCM and Skype for Business

•This feature is enabled only if the option 'Incoming Auto Forward Delay' is 'When no-one has subscribed' and and 'Incoming Auto Forward Target' is empty.

•Each device used for TPO DDI place must contain only one line extension.