The IDG500-0T002 is a 4G LTE cellular modem with an Ethernet connection. It is suitable for internet failover and other applications where internet service is not readily available. The IDG500-0T002 can be coupled with the 4G LTE service option to provide a complete cellular solution. This unit is specific to AT&T. When an AT&T 4G LTE service option is purchased concurrently, Protectli will install the SIM, configure and test the unit before shipping. If you already have your own service, then simply insert your ATT SIM into this unit (Micro 3FF size sim card).