I've a similar problem with a Motorola K3 (identified as "22b8:6402 Motorola PCS" by lsusb)
I think that this is probably a regression of NM 0.8!


Oct  7 17:57:27 ubuntu kernel: [  549.052022] usb 2-3: new full speed USB device using ohci_hcd and address 3
Oct  7 17:57:27 ubuntu modem-manager: (ttyACM0) opening serial device...
Oct  7 17:57:27 ubuntu modem-manager: (ttyACM0): probe requested by plugin 'Generic'
Oct  7 17:57:33 ubuntu modem-manager: (ttyACM0) closing serial device...
Oct  7 17:57:33 ubuntu modem-manager: (Generic): GSM modem /sys/devices/pci0000:00/0000:00:13.0/usb2/2-3 claimed port ttyACM0
Oct  7 17:57:33 ubuntu modem-manager: Added modem /sys/devices/pci0000:00/0000:00:13.0/usb2/2-3
Oct  7 17:57:33 ubuntu modem-manager: Exported modem /sys/devices/pci0000:00/0000:00:13.0/usb2/2-3 as /org/freedesktop/ModemManager/Modems/0
Oct  7 17:57:33 ubuntu NetworkManager: <info>  (ttyACM0): new GSM device (driver: 'cdc_acm')
Oct  7 17:57:33 ubuntu NetworkManager: <info>  (ttyACM0): exported as /org/freedesktop/NetworkManager/Devices/1
Oct  7 17:57:33 ubuntu NetworkManager: <info>  (ttyACM0): now managed
Oct  7 17:57:33 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 1 -> 2 (reason 2)
Oct  7 17:57:33 ubuntu NetworkManager: <info>  (ttyACM0): deactivating device (reason: 2).
Oct  7 17:57:33 ubuntu NetworkManager: flush_routes: assertion `iface_idx >= 0' failed
Oct  7 17:57:33 ubuntu NetworkManager: flush_addresses: assertion `iface_idx >= 0' failed
Oct  7 17:57:33 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 2 -> 3 (reason 0)
Oct  7 17:57:48 ubuntu NetworkManager: user_connection_updated_cb: assertion `old_connection != NULL' failed
Oct  7 17:57:48 ubuntu NetworkManager: <info>  Activation (ttyACM0) starting connection 'Vodafone Default'
Oct  7 17:57:48 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 3 -> 4 (reason 0)
Oct  7 17:57:48 ubuntu NetworkManager: <info>  Activation (ttyACM0) Stage 1 of 5 (Device Prepare) scheduled...
Oct  7 17:57:48 ubuntu NetworkManager: <info>  Activation (ttyACM0) Stage 1 of 5 (Device Prepare) started...
Oct  7 17:57:48 ubuntu NetworkManager: <info>  Activation (ttyACM0) Stage 1 of 5 (Device Prepare) complete.
Oct  7 17:57:48 ubuntu modem-manager: (ttyACM0) opening serial device...
Oct  7 17:57:48 ubuntu modem-manager: Got failure code 100: Unknown error
Oct  7 17:57:48 ubuntu NetworkManager: <WARN>  stage1_prepare_done(): GSM modem connection failed: Unknown error
Oct  7 17:57:48 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 4 -> 9 (reason 1)
Oct  7 17:57:48 ubuntu NetworkManager: <info>  Marking connection 'Vodafone Default' invalid.
Oct  7 17:57:48 ubuntu NetworkManager: Tried to set deprecated property gsm/puk
Oct  7 17:57:48 ubuntu NetworkManager: <info>  Activation (ttyACM0) failed.
Oct  7 17:57:48 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 9 -> 3 (reason 0)
Oct  7 17:57:48 ubuntu NetworkManager: <info>  (ttyACM0): deactivating device (reason: 0).
Oct  7 17:57:48 ubuntu NetworkManager: flush_routes: assertion `iface_idx >= 0' failed
Oct  7 17:57:48 ubuntu NetworkManager: flush_addresses: assertion `iface_idx >= 0' failed
Oct  7 17:57:48 ubuntu modem-manager: Got failure code 100: Unknown error
Oct  7 17:57:48 ubuntu modem-manager: (ttyACM0) closing serial device...
Oct  7 17:58:04 ubuntu NetworkManager: <info>  Activation (ttyACM0) starting connection 'Vodafone Default'
Oct  7 17:58:04 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 3 -> 4 (reason 0)
Oct  7 17:58:04 ubuntu NetworkManager: <info>  Activation (ttyACM0) Stage 1 of 5 (Device Prepare) scheduled...
Oct  7 17:58:04 ubuntu NetworkManager: <info>  Activation (ttyACM0) Stage 1 of 5 (Device Prepare) started...
Oct  7 17:58:04 ubuntu NetworkManager: <info>  Activation (ttyACM0) Stage 1 of 5 (Device Prepare) complete.
Oct  7 17:58:04 ubuntu modem-manager: (ttyACM0) opening serial device...
Oct  7 17:58:04 ubuntu modem-manager: Got failure code 100: Unknown error
Oct  7 17:58:04 ubuntu NetworkManager: <WARN>  stage1_prepare_done(): GSM modem connection failed: Unknown error
Oct  7 17:58:04 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 4 -> 9 (reason 1)
Oct  7 17:58:04 ubuntu NetworkManager: <info>  Marking connection 'Vodafone Default' invalid.
Oct  7 17:58:04 ubuntu NetworkManager: Tried to set deprecated property gsm/puk
Oct  7 17:58:04 ubuntu NetworkManager: <info>  Activation (ttyACM0) failed.
Oct  7 17:58:04 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 9 -> 3 (reason 0)
Oct  7 17:58:04 ubuntu NetworkManager: <info>  (ttyACM0): deactivating device (reason: 0).
Oct  7 17:58:04 ubuntu NetworkManager: flush_routes: assertion `iface_idx >= 0' failed
Oct  7 17:58:04 ubuntu NetworkManager: flush_addresses: assertion `iface_idx >= 0' failed
Oct  7 17:58:04 ubuntu modem-manager: Got failure code 100: Unknown error
Oct  7 17:58:04 ubuntu modem-manager: (ttyACM0) closing serial device...
Oct  7 17:58:12 ubuntu modem-manager: Removed modem /sys/devices/pci0000:00/0000:00:13.0/usb2/2-3
Oct  7 17:58:12 ubuntu NetworkManager: <info>  (ttyACM0): now unmanaged
Oct  7 17:58:12 ubuntu NetworkManager: <info>  (ttyACM0): device state change: 3 -> 1 (reason 36)
Oct  7 17:58:12 ubuntu NetworkManager: <info>  (ttyACM0): cleaning up...
Oct  7 17:58:12 ubuntu NetworkManager: <info>  (ttyACM0): taking down device.
Oct  7 17:58:12 ubuntu NetworkManager: <info>  Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)
Oct  7 17:58:12 ubuntu NetworkManager: <info>  Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)