the RFID tag antennas are designed for diferent frequency bands like in the US for UHF 902-928MHz or in japan 950-956MHz. So the reader should be configured to cover diferent regions. That it, it depends on the company, in what frequency band they are working with.
that would be rare bcoz there are restrictions over the usage of frequencies as buenrostro stated.... the company would have to get the usage frequency and other things approved before usage...