Sending a fax using your all in one copier/fax/printer isn't possible as you need a phone line to do that. If you just want to send via your PC just using a software and your PC modem then you also need a phone line to do that.
The only way you can send a fax without a phone line is by using Just Google it and you can choose from dozens and dozens of service available online.
You may also want to check Onesuite
internet fax service it charges 2.5 cents per page sent.