You can send faxes from your fax machine, from your printer-scanner-copier-fax, or even from your computer, if you have a phone line.
The thing is, the "receiving" part of it is what needs to be up-and-running and available 24/7, because those who are sending you a fax expect to be able to whenever they want to.
You can get a free eFax account to handle fax reception, if you don't receive that many faxes:
http://www.efax.com/efax-free