You can learn from this article about the NOTECHAVAILABLE and NOTECHWORKING requirements.
Important: The NOTECHAVAILABLE and NOTECHWORKING return values are only shown if the Abort sessions and show this webpage to the customer option is selected in the Administration Center on the Settings tab.
Select a Technician Group to see the NOTECHAVAILABLE requirement for private sessions.
NOTECHAVAILABLE Requirement for Private Sessions
Select a channel to see the NOTECHAVAILABLE requirement for channel sessions.
NOTECHAVAILABLE Requirement for Channel Sessions during Working Hours