Using a SIM card in Buenos Aires
Being in a big city like Buenos Aires, is very smart to be well comunicated, so the best way of do this is getting a local phone number (SIM card) in your own celphone. In this way you get a cheap line for local comunications and then you can dispose it when you finished your holidays.
For what do I need a local cellphone line?
Well, is not a bad idea to have recorded the phone number of your hotel, by example. Perhaps the phone number of a friendly taxi driver you had meet to "rescue" you from any place, and to use internet anytime.
I'm still looking for a nice place at the airport, till the moment I only found stores interested in sell you comunication plans which are more useful to the locals than easy-disposable plans (prepaid minutes based) for Visitors.
Here in Buenos Aires you can account with three brands of mobile comunications:
Movistar, Personal and Claro. No big differences between them, at least for the reduce use you will do as a tourist. I use to join my Customers of private tours here in Buenos Aires to buy a SIM card, just for help in the translation, although in the tourist area even without speaking english they should understand what are you looking for. Where to buy a SIM card? Simply, at almost any kiosk, they sell you the little craft envelope with the SIM card inside at the ridiculous price of USD 1. Any SIM card could be reduced in size to fit in smartphones.
Then, you have to buy the "minutes", or charge the SIM card, I suggest no more than USD 10 (requested in pesos to the seller), taking in mind that for the use of internet you will use only 0,30 USD per day. IMPORTANT!! Don't buy the charge of your SIM card after put it in your cellphone and activate it, because otherwise you might miss the load. You must receive an SMS letting you know that your line is activated. Usually you can buy the load of your SIM card at the same place, just bringing your phone number, the seller will charge it by internet and you will receive in seconds an SMS in spanish letting you know that your line is loaded.
Check before if your cellphone can accept different SIM cards than the one your company provides. It is usually possible, but just in case.
a. Be sure your phone would accept other SIM cards from a different company.
b. At most of the kiosk they will sell SIM cards (We call them SIM cards, no need to translate)
c. Put your SIM card in your cellphone and wait for the activation notice SMS
d. Buy (probably you can do at the same place where you bought your SIM card) the load of the SIM card (I suggest USD 10)
Well I hope all my experience as private tour guide in Buenos Aires result useful for you!