Cancel a RingCentral Fax in progress

Press cancel button on fax machine?  Or unplug it?

We also need a function to cancel outgoing faxes that have been submitted through RingCentral.  Our users sometimes send outgoing faxes to the wrong phone number (using email to @rcfax.com).  When they do it repeatedly by mistake, they need an option to cancel the fax so that they are not bothering recipients' voice lines.

I believe the originator of this request is referencing a similar issue, not a physical fax machine that can be unplugged.