Confusing.. fake calls to phones? Really legit?

[bpccccqd]

I found a website callitfake.com from a friend on his blog and it allows you to type in a message and send calls to other users.  The neat thing about it is it seems to spoof the caller ID some how.  When you send a message, it shows the number you typed into the FROM field and the name you put into the NAMe field.  

Once you enter the information into the form above, the number you chose to dial will be phoned and the selected voice will read the message entered. The caller id number can be made up, however it most be in the correct phone number syntax ie: 444-414-0000. Both numbers must include the area code for this form to work. Once populated and submitted your request is transfered to cdyne where the call is created.

Any one know how they're doing this?  I'm curious, I would like to do something similar without having the demo message at the end about CDYNE.  Check it out when you get the oppurtunity and reply if you know of any other options, how-tos etc.  None the less callitfake is pretty fun to use to mess with friends.