How do I buy a SIM card for my cellphone in Paris? Also, is there anything I should keep an eye out? (things like fees, cellphone-compatibility in europe...) and do they have pre-paid plans (in Brazil we have those, I don't know how it's called in other parts of the world, but its simply a plan wich you pay before using, and once your credit is over you cannot make any more calls before recharging the SIM card).
If you know any, please post some buying places near the Arc de triomphe.
Slightly more than a year ago, on 2011-12-30 CET, as a German citizen, I bought a prepaid card in an Orange shop in forum des Halles / Les Halles, Paris. That's an 11 min travel by public transport (RER A) from Arc de Triomphe. The price for the card was 5 EUR, incl. 5 EUR of credit. I then charged the card with 15 EUR, bought at a Phone House just around the corner, because in the Orange shop that was not possible.
The Orange card has an option called Internet max that can be activated either in the SIM card menu somewhere under Multimedia, or online. See the screenshot below: Currently it offers 500MB for 9 EUR per month. Activation of the option took some hours. Tethering did not work, but I believe that it's possible to hack around that. Note that in the shop they told me that with a standard Orange prepaid card the data option is not available. They are wrong!
Very good option is http://www.lefrenchmobile.fr/ They have a pre-paid card with a reasonable price. The good thing is that you don't have to sign any contract, give them any account number or whatever. You just buy a SIM card and a credit in their e-shop.
You can have the card shipped all around the world. It is activated once you make your first call, and at that moment you are assigned a phone number, too. Once you don't want it, you simply drop it. They diminish EUR 1.40 every month from it if you don't use it, and once you have no credit left, the account is terminated.
I have it and I'm really content with it. All service is in English, the delivery (inside Paris) was within couple days.
I know this is not a "buy near Arc de Triomphe" option, but still, it is valid as an answer for future visitors of the question.
Another option is the operator http://free.fr/ that launched their first shop at 8 Rue de la Ville-l'Évêque, 75008 Paris in the North-Center Paris, close to many metro stations (lines 8,9,12,14 and others). It has become very popular and they have tariffs as cheap as EUR 2 a month.
