AIS staff assures me that its THB1400 21 mbps is usable with other country's data service providers. But I think she is a saleswoman not totally aware of the limitations of her company's products. Anyone have experience usibg their card and then using it with a different SIM in Singapore, China, Philippines, etc?

The other factor that has me concerned is the LINEUPS at MBK's dealerTelewiz (!) . But don't all these telecommunication companies in Thailand have long waits for service? Some of the staff seem half asleep too. True seems to have more service centres and more on the ball staff. Don't know about DTAC.

Is there a 'Mercedes' of mobile and service providers, where if you are willing to pay a higher price you get superior coverage, superior service and faster speeds?

http://www.ais.co.th/mobileinternet/aircard/3g-21-mbps/

I believe that any branded air-card purchased here in Thailand, whether from AIS, DTAC, TrueMove/H is un-locked and can be used with any other SIM, either here in Thailand or in Singapore, China, Philippines.

That said, an air-card from AIS is likely to support 900/1900/2100 MHz 3G so would not necessarily work on any 3G/4G/LTE networks which do not operate on those frequencies.

It is true that air-cards branded in some/many other countries may indeed be "locked", but it may also be relatively easy to unlock those if necessary.

Assume you are asking about Thailand, re: a 'Mercedes' of mobile and service providers? No, not that I am aware of.

I just rounded up some common sense and called an English-speaking operator at AIS (1175+2+1+0). She concurs with the qualification that the foreign service must be operating on the same frequency as the device, there are three or four, one of which is 700 something, one 900 something and another is 2100 (total co-incidence with 2100 speed, she assures me).

Sorry, forgot to add...

Most/all air-cards will also support GSM data (900/1800 MHz) for slower speed 2G data (GPRS/EDGE).