If you search the web you'll find conflicting reports about Magic Jack and the ability to fax. When I had DSL, I was able to fax but feared that now with a wireless hotspot I'd be SOL. Happily, its not true! Specifics: My desktop, a 5-yr old HP Pavillion Elite m9150f has the ability to connect to a wireless router. (In this case my "hotspot" from ATT) My fax is actually a multi-purpose Canon MX850 I have the Magic Jack Plus. The MJ-Plus is plugged into the USB port of the computer. The phone line from the Canon printer/scanner/fax is connected to the back end of the Magic Jack. I faxed a 2-page document containing medical records to my health provider. Just today I received snail-mail confirmation of receipt of the document.
Well I did it, I plunged into the VoIP with a magic jack. I figured it's nice to have a 2nd phone line for say my basement instead of the wife calling my cell phone. Was really easy to set up. All I had to do was plug it in and before I knew it I got to pick my phone number. One thing that wasn't explained well, I felt like I had to catch this one. It was the outbound thing in the setup. If you are not careful and don't put a check in the box you won't have inbound dialing capability. It didn't seem like that was explained quite so well. Like they could have put a "If you want people to be able to call your magicjack click this box" or something like that.
Small update: So far, I have only encountered one target fax number that wouldn't connect. It was with the Social Security Administration.
My Nettalk DUO works well, for when I need to fax. I rarely have need to do it, until a couple times, recently. I'm glad I bought a multifunction printer/scanner/fax. I don't need to have my PC on, to send an already printed sheet.