Found Personal to be a convenient/fast solution for calls/internet access.
1.- SIM may be purchased w/o hassle at many street press stands. Look for signs reading "venta de chips personal, movistar, claro" Price 12 Pesos (some 2 EUR).
2.- As sold chip holds no credit. Recharge with min 15 Pesos (carga virtual) or min 25 pesos (scratch card).
3.- To activate dial *151
4.- Purchase Pack "Todo incluido" for 15 Pesos to get 25 Mb to use in 7 days. To do so choose "Autogestión/Comprar Pack/Pack todo incluido" in the Personal Sim menu.
5.- Find an international phone card with a local access number / use voipbuster, etc. and choose the access number as a "número amigo". Use *152 to this end. Then buy pack "llamadas número amigo" to get 12 hours of calls to that number to use in 5 days. Price 9 pesos.
6.- All in all everything you need to stay in touch in Argentina for a week for about 7 EUR. On my Blackberry 8520 (no 3g), I got EDGE in BsAs and EDGE or GPRS in Calafate and Iguazú.
