3G is used by mobile networks not with land connections and you have to use either a 3G capable air card or a 3G mobile phone and USB connection to recieve it.
CAT Telecom already have this and a few of my friends use it, the maximum speed is between 2.5Mb and 3Mb, it works fine in Udon Thani and Nong Khai provinces, but a friend took his laptop to Bangkok and Pattaya and it didn't work there, the CAT Telecom staff in their office in Pattaya told him it doesn't work in Chonburi province or Bangkok and is only available in 51 of the 76 provinces.
You can get an 8Mb connection anywhere if you want to pay thousands for a commercial connection, I know a couple of programmers who work online that have it, but it's very expensive.
I hope this was helpful.
