Need suggestions about buying a temporary phone for our trip to Paris. Do we wait and buy one in Paris or get one in the US before we go? I do not have an unlocked phone to take with me.

You can easily get one in the US on EBay or Amazon. Search for an "unlocked GSM quadband phone". You can get a simple phone for talking for around $30, or an Android phone for under $100.

I guess then the next dumb question is how do I use it? do I just get a sim card from orange etc.. put it in the phone and voila?

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I guess then the next dumb question is how do I use it? do I just get a sim card from orange etc.. put it in the phone and voila?
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Yes. Try to pick one of orange's larger stores to increase your chances of having an English speaking clerk. Or you could get a SIM in advance from http://www.lebara.fr if you get creative with your address in the order form. Or have one mailed to your hotel so it's there when you arrive.

I've an old Nokia I'd sell you for $10 plus shipping, if you live in the US, and if you don't need/want a smart phone. Yes, it's as simple as you said. Or, you could take it to France as is, and get a cheap Orange card in CDG as soon as you get off the plane, before you even get your luggage.

<i>get a cheap Orange card in CDG as soon as you get off the plane</i>

Where is this Orange boutique at CDG, located before baggage claim? Where is there an Orange boutique anywhere at CDG?

Relay sells SIM cards.

Relay or any other tabac or magazine store at CDG sells SIMs from Lebara, Lycamobile, or maybe Ortel. I have never seen Orange, SFR, or Bouygue SIMs sold anywhere at CDG.