We have a cheap £40 plain paper fax machine but with no ink in it as we only use it for sending, not receiving. I tell everyone we don't have one so no-one tries to send us anything and we certainly don't get any junk mail.
We use it for the following:
1. sending payment details to USA suppliers - they will only accept fax confirmations of card details
2. completing new supplier credit forms - again, in the ragtrade which is way behind any other sector, some things are only accepted by fax
3. when a customer makes multiple attempts at ordering online, the bankds set aside their money for authorisations, they then have no money to spend and the banks will only accept a fax from us to return the money to the customer's account
4. when you need to get a letter to someone quickly - usually something official with a time limit - when email doesn't work
It's just useful to have it but for our benefit, not for anyone else's.