Interesting thread...good info.

I will be visiting Bangkok next week as well and I was interested in finding out a few options:

1. I have a I9020T from Samsung(Nexus S)...which only operates on 3G on 900 / 1700 / 2100 MHz UMTS...Will I be able to receive 3G on either AIS/DTAC/Tru?

2. I also have an ASUS TF101 which doesnt have a sim card capability...so I need a portable WIFI solution as well...looks like AIS has a Pocket WIFI which offers this---any other options? I dont want to be stuck with EDGE or with HotSpots for sure.

Thanks for the info.
K

Check out this post, according to which your Nexus S would work on AIS and on TOT3G.
By the way Huawei has recently released the first pentaband 3G handset running Android, the Ascend P1, which virtually supports all the global 3G frequencies used today (850, 900, 1700/2100, 1900, 2100). It only lacks some Japanese frequencies (700 and 1700), which are of minor relevance.

Thanks..
Any idea about the pocket wifi or something similar?

As there isn't any pocket wifi supporting all the Thai frequency bands we can hardly recommend any pocket wifi unless you contain potential operators.

From what I saw...AIS is the only one that offers the Pocket Wifi(which believe is the HUAWEI_E583X). It seems that it works at 7.2MB/s.

Also, I just saw something confusing on AIS's website...that their 900 frequency band for 3G is for CDMA? I thought it was all GSM??

Any ideas?

they refer to WCDMA which is another word for 3G/UMTS, which is strictly spoken not GSM/2G.

You don't necessarily need to buy the device from the operator which you intend to use. Just make sure it's unlocked and supports the required 3G frequency.

What they run on 900 MHz is a UMTS network, which sometimes is also designated as "WCDMA", "HSPA" or "3G" and in the US such networks are even considered "4G" once they support very high speeds using HSPA technology.
GSM in contrast is the predecessor standard that is also called "2G". UMTS evolved from the GSM standard, that's why UMTS devices are always backwards compatible to GSM.

Both are incompatible with the American CDMA/EV-DO standard which is also called "3G".

2G, 3G and 4G are rather non-technical terms that describe the 2nd, 3rd and 4th generation of radio standards which are not necessarily compatible with each other.

Please note that in Thailand you can also buy tariffs and devices for CDMA / EV-DO network. But from TOT and not from AIS.

Perfect...thanks. The one listed on the AIS website only offers 7.2 Mbps/s.
I found a few more that support 21 Mbps/s here:
???????????? 3G Router ???? ??? ??? ???? ??? ??????? ????

I'll try and get one of these assuming that they are unlocked and can utilize some of the 42Mbps speeds being offered by AIS or TOT?

As far as the sim for the cell goes--it seems like both AIS or TOT would work as AIS would give me 3g on 900 and TOT on 2100(both which the Nexus S supports).

Anyone have real world experience with which of these services truly have good coverage at those speeds? I plan to stay in Bangkok throughout with little or no travel to other parts of the country.

In any case buy a mobile hotspot from Huawei or ZTE as most of the other stuff is of low quality. Unfortunately I am not aware of any mobile hotspot that would support American 3G frequency bands besides the Thai ones, so whichever device you select it will be rather useless back in the Staats. There are only USB modems that support all five global UMTS frequencies (850, 900, 1700/2100, 1900, 2100) and thus are called "pentaband", such like the Huawei E369.