Some guys over at ADVrider forum had this to say:

Hi CameraTraveler,

Wifi skype calls and internet access are the shizzle. Much faster than third world cellular data. The advantage of wifi is that it is free and pervasive. Sure you could get a prepaid sim for Argentina at:

Argentina SIM Card - Prepaid cell phone service for travelers

But cellular data transmission rates would be glacially slow compared to wifi. And it is EXPENSIVE. 10.00/megabyte for the above plan. (Which is cheaper than the cellular roaming charges you would have to pay if you use your ATT Iphone sim. Currently 15.00/meg for data international roaming).

And when you get to Chile it is useless and you need to get another phone sim or cellular laptop modem from a Chilean carrier.

I used an Ipod touch to email and post ride reports on a recent trip to Panama and back this spring. Many others use inexpensive netbooks for posting ride reports and uploading pictures to the internet and making skype calls home. In every country you can find wireless internet even in unexpectedly out of the way places. It was fast and it was free. I would just walk around, even in rural Honduras in the little town next to the Copan Ruins until I got a free wifi hotspot and stand in the street and type away. Even in the jungle in southern Costa Rica there was a guesthouse with satelite internet access and wireless router where I stayed for a week for ten bucks a night. If the wifi was password protected I would ask for the password at the cafe or nice hotel I was walking by if I was in a town and they would write it down on a piece of paper. In fact I am typing this and sending it to you on a wifi connection from my nice neighbor across the street. He wrote down his password and let me use his wireless router since the signal comes in over at my house. I am gone alot riding around the world and don't want to pay for internet access I don't use.

Also, there are internet cafes and places with internet access all over the place for 1.00/hour or so. At least there were all over Central America. I had to stop at the Darien gap 30 miles short of South America but I imagine it is much the same there. I am heading to South America next winter, but am offering some suggestions until someone who has a better answer chimes in.

If you are camping in the boonies and there isn't any wifi in a small town nearby, there probably aren't any cell towers around for cell phone service or usb cellular modems for your laptop either I should think. Or places to plug in your laptop and cellphone to recharge the batteries.

Camping half the time in South America sounds nice on paper, but if you can stay in a nice place in a small village in Peru or Bolivia or whereever with breakfast served and wifi for under ten bucks while charging up your internet devices, the camping generally tends to play a more minor role in ones travels. And of course, part of the fun of travel is meeting interesting people in hostels and out of the way guesthouses out in the boonies.

Just some thoughts.

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When I was riding down south I didn’t feel like camping until Chile. The areas in Argentina and Chile that I wanted to camp had no cell coverage. In Patagonia, outside of the towns, you’ll not find any cell coverage either. In the towns there is always a place to get wifi (unless a large earthquake happens to hit Chile) and hostels are so cheap, with free wifi, that it doesn’t make sense (to me) to camp in a town.

If you must have access all the time then I would start looking into sat phones with data plans.