Here is a very good review on the Inrico TM-7. I hope you enjoy the video.
Cellphone operators compatibility
All our network radios work with GSM operators. In the USA, they will only work with AT&T (3G and 4G) and T-Mobile (3G). Note that AT&T will buy any contract you may have with other operators, so you can easily change carrier. The radios will also work accessing any WiFi hotspot.