Free Internet Fax

Which one is the best to send free fax from computer using online service without fax machine? I don't like any fax service with monthly fee. I don't like to provide my credit card number for a free trial. I like these below fax services because they are free. So, what is the catch?

Are they reliable and secure? How about the privacy of our faxes?

http://www.myfax.com/free/
MyFax Free lets you send a fax for free to over 40 countries. This free faxing service is provided by Protus IP Solutions.
* Please note that existing MyFax® customers cannot use this free Service.
MyFax® is a trademark of j2 Global Communications, Inc. and its affiliates.

http://faxzero.com/
Free Fax
Ad on the cover page
Fax 1 document — max 3 pages
Max 2 free faxes per day

http://www.bestfreefax.com/freefax.php
Send a Free Fax
No Setup Fee
Free Outbound Faxing
No Credit Card Required
Instant Activation

http://www.gotfreefax.com/
Free Fax Service
Truly FREE!
Free fax cover page, No Ads
3 pages per fax maximum
2 free faxes per day maximum