The easiest-to-use card that I have found is that telephone card that you get from 'Tabac's. Look on the street for a shop with a a Tabac sign -- some are magazine/news shops, others are bars. Ask for "une carte de téléphone -- la plus petite" (sorry if this isn't the official term, Paris people, but it works for an American who speaks French like an American who speaks French).

The cards work in telephone booths, but not in hotel rooms. Here's how to use it:[list=1][*]Take the phone off the hook.[*]Insert the telephone card into the slot. Wait until the display on the phone shows you how many units ('unites') remain on the card.[*]Dial the number. The instructions in the phone booth tell you the code you need to dial first if it's an international call.[*]After you connect to the person you're calling, units are automatically deducted from the card, and the remaining number of units are automatically displayed on the telephone.[/list=a]

I've found this system to be 1000 times easier and lots cheaper than the cards where you have to dial a toll-free number, enter your crad's number, then dial the number you really want to call.

I don't have exact $$ figures, but a 10-minute call to the U.S. from Paris using a telephone card is no more than $2-3, if that.