Here's the list:
4G: They have to be in Band 4 which is AWS frequency.
3G: We need AWS 1700/2100. If it only lists 2100, it will likely not be sufficient since international companies use 2100 for both uplink and downlink. We just use it for downlink.
2G: 1900 MHz
We are looking at the Samsung Galaxy S3 T999, as an example, but we are looking at all different price points.