We are a medical clinic and sometimes when we are closed for more than a week, we want to disable the fax so that messages are not received and the sender knows that their fax was not received. If we cannot do this, we have to respond to every fax and inform them we are closed, etc. It causes legal issues also if we receive a fax and do not respond.
We ended up having to move my company fax to an auto-attend number instead and set that to voice only. We think that will work, as fax is not received. Hope that the fax sender is also getting an error or a busy, etc so that they know the fax was not sent.