To answer your question Can it work without a phone? The answer is YES!!! Believe it or not with the magic jack it includes software built into the unit for free. Not only will it allow you to dial out but it also allows you to receive calls directly over your computer or laptops microphone and speakers.
When your magic jack is plugged in and loaded up, there will be a feature in your menus that will ask you how you would like to make and receive calls. You will be able to choose “headset and microphone” or “phone”.
My personal preference is to use a home phone that I connect to the magic jack, the feature of not using a phone to call and receive phone calls, did come in handy when I traveled. It is not convenient to bring a phone when you travel so this is where I mainly use the built in feature.
A lot of people asked me what type of phone is compatible with the magicjack. The answer to this is any phone that has a regular phone cord.
Can you use the magicjack and have it hooked up so that more than one phone in the house rings? Well let me tell you this. What I have done in the past is have a magic jack unit hooked into a cordless phone base. This base phone allows me to connect up to 4 phones. So what I had setup was when someone called my number the main base rings, and then the main base sends the signals to the other phones in the house. I also came across a guy who has a setup like none before. If you are real interested, in youtube type in magicjack on many phones setup.
Below is a screen shot of the option to use the magic jack without a home phone.