I've been using Telefonica Movistar prepaid SIM card for Internet access via GPRS/EDGE for my laptop since my arrival in Chile (June, 2008). They offer 24 hours of Internet access (unlimited) for 2000 pesos.
With regards to the above mentioned service, I am sorry to say, that I've had extremely negative experience. I would wish Telefonica Movistar to start loosing clients.
Sorry Movistar, but you have personally offended little Chookcha...


