NetworkManager: <info>  Activation (ttyUSB0) starting connection 'AT&T'
NetworkManager: <info>  (ttyUSB0): device state change: 3 -> 4 (reason 0)
NetworkManager: <info>  Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) scheduled...
NetworkManager: <info>  Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) started...
NetworkManager: <info>  Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) complete.
NetworkManager: <WARN>  stage1_prepare_done(): GSM modem connection failed: Sending command failed: 'Resource temporarily unavailable'
NetworkManager: <info>  (ttyUSB0): device state change: 4 -> 9 (reason 1)
NetworkManager: <info>  Marking connection 'AT&T' invalid.
NetworkManager: <info>  Activation (ttyUSB0) failed.
NetworkManager: <info>  (ttyUSB0): device state change: 9 -> 3 (reason 0)
NetworkManager: <info>  (ttyUSB0): deactivating device (reason: 0).
NetworkManager: flush_routes: assertion `iface_idx >= 0' failed
NetworkManager: flush_addresses: assertion `iface_idx >= 0' failed