What would be the best SIM card / package to get for a visitor to Thailand staying a month or so?

They would be unlikely to use over 50 MB a day data. Perhaps it would be possible to use Skype or an alternative on a smart phone so as to make outgoing calls using the data allowance.

Thank you for your suggestions!

Somebody recommended TrueMove.

They have coverage in the areas I would like.

Their webpage has an English version, but it is all in Thai! Even Google Translate doesn't help much, as all the details are in images with Thai writing.

1 ) Does anybody have experience with TrueMove? Are they all right as a provider?

2) I think I would tether my phone to a computer when I want to go on the Internet, too. Does their iphone 4 micro-SIM work with older iphones, too or should I use the Hi-Speed net SIM?

3) Will the pre-paid package / SIM let me receive phone calls on my phone as well as work for getting data on the internet?

4) Are those SIM cards/packages easy to get hold of? Could I pick one up at any convenience store?

Thank you for your help!

Truemove-H will give you the best coverage area. I use the iPhone micro sim in my Samsung so I'd guess it will work in any iPhone.

You can buy a 30 day package that will give you 1GB 3G for 350 baht plus you would need to add about 150 baht for phone calls. After you buy 500 baht credit, install the sim card and dial *900*43# and press call. That will buy the 3G 1GB package. The balance of the 500 baht will be credit on the phone for calls. If you happen to use up the 1GB, you can buy another 350 baht credit and repeat the above. That will give you another 1 GB of 3G.

ADDED - You can get the sim card and buy credit at a 7-11.