Free Internet Fax Options
The first thing you should know is there are several ways to send or receive a fax via the internet. The first way is through email. You write an email and put the fax number in the "to" field, then you send it off to the recipient. The second method is via an online web form that you fill out to fax. Some of these will allow you to upload a document as well as use text. Others only allow text to be sent. The plus to this is that you have no system requirements. The third is via software that your provider gives to you where you can upload your document to fax it off.
The big services that used to be free now only allow a 30 day free trial. Those two are eFax and JFax. Both are excellent, but now charge for their services. You can also check with your ISP, as some offer faxing services as well. My hosting company, GoDaddy, offers faxing services with my domain hosting for less than $3 per month. Free services are now few and far in-between unless they are bundled with another service, like your internet, dsl, fios or cable connection.
FaxZero.com has both a free and a premium option. For the free option, you can use a web form to send up to 2 free faxes daily. You can fax one document with a maximum of 3 pages each. In order to keep it free, there will be an ad placed on your cover sheet.
For text faxes only, there is http://www.gujarat4u.com/freefax.html. The website looks really cheap, but this works wonders anywhere in the world. Don't let the simplicity fool you. If you want to send a document, however, this isn't the place to do so.
For receiving faxes only:
K7 (http://www.k7.net/) allows you to receive incoming faxes and voicemail for free. The incoming faxes are converted to .tiff files and the voicemail is converted to .wav format. You can listen to them right on the K7 site. They give you a free phone number, however sometimes it may not be in your local calling area.