iPhone as Mobile Broadband connection for laptop on the road - South America:

Hello everyone! First post here. Been researching a 4 month trip to Buenos Aries and other places in South America and looking for people who have first hand experience with how reliable the reception of using their iPhone as a phone in South America and building upon that answer -

- the second part of my question is if you have first hand experience using the iPhone or Mobile Broadband equipped (not WiFi) laptop on the road in South America.

It will probably help to know where I'm going and what I hope to do.

I'll be in Buenos Aires for about a month (I know WiFi/Broadband wont be a problem there) BUT then its off to Chile, Peru and Brazil, during which time I plan on camping half of the time and hostels the other for the next 3 months. I'll be bring my own laptop and need to be able to have internet access in those settings for anywhere from 1 to 4 hours a day and expect to be in each location anywhere from 1 to 10 days. Also I would occasionally need to download files as large as 200Mb.

I understand WiFi is faster but considering the camping I will be doing I'm wondering if using a laptop with built in Mobile Broadband or perhaps tethering a iPhone to the laptop will be a realistic/convenient solution to getting internet on the road in these regions.

If not, what other alternatives do you suggest I look into? The more technical or specific info for a solution the better.

Anyway nice to meet everyone and thanks guys!

-CameraTraveler