Hi I will be backpacking around Thailand for 2 months, with an iPhone which does not support CDMA. I sometimes have this tethered to my ultra mobile tablet PC. I don't want to purchase any USB sticks.

I just want to be able to get a SIM card and load some credit, which would be used only for mobile broadband not for making phone calls. The closest thing to a monthly unlimited plan is what I want.

Speed would be nice, but even just GPRS/EDGE with decent coverage would be better. If there are coverage maps around to compare the providers that would be sweet. Reliability (for thailand of course) would be important as well.

I will also be travelling right through Asia, including Vietnam, Cambodia, Laos, Malaysia so if there is a telco that has a solution that is region wide or an easier way than getting a different SIM card in each country, that would be great news.

GPRS/EDGE has virtual nationwide coverage.

Both AIS and Dtac (the two biggest operators) have unlimited packages, priced at around 1000 Baht.

I think on AIS you can get a blackberry package for less, and it also includes unlimited internet. However I assume that is only available post-paid, for which you would need a work permit to be able to subscribe to. The 1000 Baht unlimited packages are available pre-paid.

And in Thailand unlimited is just that, on 24/7 and no limit on data transfer.