To answer my own question; this device can be unlocked (although ATT customer service did not provide much help) Once unlocked it can use SIM cards from other operators and it works as long as the frequencies on the new operator's network is supported by the device. (AWS - Band 4 for LTE)
I find it odd that ATT customer service denied my request to unlock it. Claming hotspots could not be unlcoked) I thought they were required to? CTIA Consumer Code for Wireless Service includes all devices, including Hotspots.