
*** Bug Reference: 			https://bugzilla.gnome.org/show_bug.cgi?id=665630

*** Distribution name and version:	Kubuntu 12.04

*** Kernel version:			3.2.0-37-generic

*** Network device's brand and model:	Huawey E156G

*** Network Manager version:		
$ NetworkManager --version
0.9.4.0

*** Modem Manager version
$ aptitude show modemmanager | grep -i version
Versione: 0.6.0.0.really-0ubuntu1

*** Configured NetworkManager to log:
$ sudo dbus-send --system --print-reply --dest=org.freedesktop.NetworkManager /org/freedesktop/NetworkManager org.freedesktop.NetworkManager.SetLogging string:"debug" string:""
method return sender=:1.5 -> dest=:1.38 reply_serial=2

*** Stop NetworkManager:
$ sudo service network-manager stop
network-manager stop/waiting

$ sudo killall -TERM modem-manager
modem-manager: nessun processo trovato

$ sudo modem-manager --debug

ModemManager logs:

modem-manager[1828]: <info>  [1359722480.134912] [main.c:167] main(): ModemManager (version 0.6.0.0) starting...
modem-manager[1828]: <info>  [1359722480.144924] [mm-manager.c:158] found_plugin(): Loaded plugin 'Huawei'
modem-manager[1828]: <info>  [1359722480.148874] [mm-manager.c:158] found_plugin(): Loaded plugin 'Sierra'
modem-manager[1828]: <info>  [1359722480.148974] [mm-manager.c:158] found_plugin(): Loaded plugin 'Wavecom'
modem-manager[1828]: <info>  [1359722480.149056] [mm-manager.c:158] found_plugin(): Loaded plugin 'AnyData'
modem-manager[1828]: <info>  [1359722480.149136] [mm-manager.c:158] found_plugin(): Loaded plugin 'SimTech'
modem-manager[1828]: <info>  [1359722480.149217] [mm-manager.c:158] found_plugin(): Loaded plugin 'X22X'
modem-manager[1828]: <info>  [1359722480.149296] [mm-manager.c:158] found_plugin(): Loaded plugin 'Ericsson MBM'
modem-manager[1828]: <info>  [1359722480.149376] [mm-manager.c:158] found_plugin(): Loaded plugin 'Option High-Speed'
modem-manager[1828]: <info>  [1359722480.149455] [mm-manager.c:158] found_plugin(): Loaded plugin 'Longcheer'
modem-manager[1828]: <info>  [1359722480.149535] [mm-manager.c:158] found_plugin(): Loaded plugin 'MotoC'
modem-manager[1828]: <info>  [1359722480.149613] [mm-manager.c:158] found_plugin(): Loaded plugin 'Linktop'
modem-manager[1828]: <info>  [1359722480.149692] [mm-manager.c:158] found_plugin(): Loaded plugin 'ZTE'
modem-manager[1828]: <info>  [1359722480.149772] [mm-manager.c:158] found_plugin(): Loaded plugin 'Samsung'
modem-manager[1828]: <info>  [1359722480.149851] [mm-manager.c:158] found_plugin(): Loaded plugin 'Nokia'
modem-manager[1828]: <info>  [1359722480.149930] [mm-manager.c:158] found_plugin(): Loaded plugin 'Gobi'
modem-manager[1828]: <info>  [1359722480.150056] [mm-manager.c:158] found_plugin(): Loaded plugin 'Novatel'
modem-manager[1828]: <info>  [1359722480.150136] [mm-manager.c:158] found_plugin(): Loaded plugin 'Option'
modem-manager[1828]: <info>  [1359722480.150308] [mm-manager.c:158] found_plugin(): Loaded plugin 'Iridium'
modem-manager[1828]: <info>  [1359722480.151696] [mm-manager.c:158] found_plugin(): Loaded plugin 'Cinterion'
modem-manager[1828]: <info>  [1359722480.151778] [mm-manager.c:158] found_plugin(): Loaded plugin 'Generic'
modem-manager[1828]: <info>  [1359722480.151869] [mm-manager.c:210] load_plugins(): Successfully loaded 20 plugins
modem-manager[1828]: <debug> [1359722480.152528] [mm-manager.c:1057] mm_manager_start(): Starting device scan...
modem-manager[1828]: <debug> [1359722480.155858] [mm-manager.c:875] device_added(): (tty/ttyS0): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.162957] [mm-manager.c:875] device_added(): (tty/ttyS1): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.163345] [mm-manager.c:875] device_added(): (tty/ttyS10): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.163740] [mm-manager.c:875] device_added(): (tty/ttyS11): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.166493] [mm-manager.c:875] device_added(): (tty/ttyS12): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.166867] [mm-manager.c:875] device_added(): (tty/ttyS13): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.167235] [mm-manager.c:875] device_added(): (tty/ttyS14): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.167601] [mm-manager.c:875] device_added(): (tty/ttyS15): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.167988] [mm-manager.c:875] device_added(): (tty/ttyS16): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.168353] [mm-manager.c:875] device_added(): (tty/ttyS17): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.168736] [mm-manager.c:875] device_added(): (tty/ttyS18): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.169103] [mm-manager.c:875] device_added(): (tty/ttyS19): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.169466] [mm-manager.c:875] device_added(): (tty/ttyS2): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.169843] [mm-manager.c:875] device_added(): (tty/ttyS20): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.170208] [mm-manager.c:875] device_added(): (tty/ttyS21): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.170732] [mm-manager.c:875] device_added(): (tty/ttyS22): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.171099] [mm-manager.c:875] device_added(): (tty/ttyS23): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.171471] [mm-manager.c:875] device_added(): (tty/ttyS24): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.171832] [mm-manager.c:875] device_added(): (tty/ttyS25): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.172242] [mm-manager.c:875] device_added(): (tty/ttyS26): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.172617] [mm-manager.c:875] device_added(): (tty/ttyS27): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.172980] [mm-manager.c:875] device_added(): (tty/ttyS28): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.173344] [mm-manager.c:875] device_added(): (tty/ttyS29): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.173710] [mm-manager.c:875] device_added(): (tty/ttyS3): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.174074] [mm-manager.c:875] device_added(): (tty/ttyS30): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.174474] [mm-manager.c:875] device_added(): (tty/ttyS31): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.174845] [mm-manager.c:875] device_added(): (tty/ttyS4): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.175210] [mm-manager.c:875] device_added(): (tty/ttyS5): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.175572] [mm-manager.c:875] device_added(): (tty/ttyS6): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.175937] [mm-manager.c:875] device_added(): (tty/ttyS7): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.176974] [mm-manager.c:875] device_added(): (tty/ttyS8): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.177411] [mm-manager.c:875] device_added(): (tty/ttyS9): port's parent platform driver is not whitelisted
modem-manager[1828]: <debug> [1359722480.178863] [mm-manager.c:859] device_added(): (tty/ttyprintk): could not get port's parent device
modem-manager[1828]: <debug> [1359722480.184550] [mm-manager.c:1075] mm_manager_start(): Finished device scan...

*** After plugin, when the device can work (after the NetworkManager has been started), ModemManager logs:

modem-manager[1828]: <info>  [1359722661.690635] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB0) opening serial port...
modem-manager[1828]: <warn>  [1359722661.695604] [mm-serial-port.c:407] real_config_fd(): (ttyUSB0): port attributes not fully set
modem-manager[1828]: <debug> [1359722661.700329] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 1 (open)
modem-manager[1828]: <debug> [1359722661.700588] [mm-plugin-base.c:1064] try_open(): (ttyUSB0): probe requested by plugin 'Huawei'
modem-manager[1828]: <debug> [1359722661.801827] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT^CURC=0<CR>'
modem-manager[1828]: <debug> [1359722662.975961] [mm-serial-port.c:697] data_available(): (ttyUSB0) unexpected port hangup!
modem-manager[1828]: <debug> [1359722662.976053] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 0 (close)
modem-manager[1828]: <info>  [1359722662.976126] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB0) closing serial port...
modem-manager[1828]: <info>  [1359722662.976232] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB0) serial port closed
modem-manager[1828]: <warn>  [1359722662.976697] [mm-plugin-base.c:856] real_handle_probe_response(): Couldn't probe for capabilities, probably not a GSM or CDMA modem

--- after plugin, should be also more verbose sometimes ---

modem-manager[1736]: <info>  [1359723705.938584] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB0) opening serial port...
modem-manager[1736]: <warn>  [1359723705.938999] [mm-serial-port.c:407] real_config_fd(): (ttyUSB0): port attributes not fully set
modem-manager[1736]: <debug> [1359723705.939123] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723705.939214] [mm-plugin-base.c:1064] try_open(): (ttyUSB0): probe requested by plugin 'Huawei'
modem-manager[1736]: <debug> [1359723706.039802] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT^CURC=0<CR>'
modem-manager[1736]: <debug> [1359723707.227924] [mm-serial-port.c:697] data_available(): (ttyUSB0) unexpected port hangup!
modem-manager[1736]: <debug> [1359723707.228014] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723707.228055] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB0) closing serial port...
modem-manager[1736]: <info>  [1359723707.228125] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB0) serial port closed
modem-manager[1736]: <warn>  [1359723707.228353] [mm-plugin-base.c:856] real_handle_probe_response(): Couldn't probe for capabilities, probably not a GSM or CDMA modem
modem-manager[1736]: <debug> [1359723715.275421] [mm-manager.c:536] try_supports_port(): (Huawei): (ttyUSB1) deferring support check
modem-manager[1736]: <debug> [1359723715.294553] [mm-manager.c:536] try_supports_port(): (Huawei): (ttyUSB3) deferring support check
modem-manager[1736]: <debug> [1359723715.302183] [mm-manager.c:536] try_supports_port(): (Huawei): (ttyUSB2) deferring support check
modem-manager[1736]: <info>  [1359723715.317304] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB0) opening serial port...
modem-manager[1736]: <warn>  [1359723715.322757] [mm-serial-port.c:407] real_config_fd(): (ttyUSB0): port attributes not fully set
modem-manager[1736]: <debug> [1359723715.322880] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723715.322974] [mm-plugin-base.c:1064] try_open(): (ttyUSB0): probe requested by plugin 'Iridium'
modem-manager[1736]: <debug> [1359723715.423434] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723716.124136] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- 'AT+GCAP'
modem-manager[1736]: <debug> [1359723716.126758] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR>'
modem-manager[1736]: <debug> [1359723716.128131] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+GCAP: +CGSM,+FCLASS,+DS<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723716.128480] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CGMI<CR>'
modem-manager[1736]: <debug> [1359723716.828891] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- 'AT+CGMI'
modem-manager[1736]: <debug> [1359723716.832513] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR>'
modem-manager[1736]: <debug> [1359723716.833636] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>huawei<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723716.833959] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CGMM<CR>'
modem-manager[1736]: <debug> [1359723717.537717] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- 'AT+CGMM'
modem-manager[1736]: <debug> [1359723717.538781] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR>'
modem-manager[1736]: <debug> [1359723717.544232] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>E156G<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723717.544488] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723717.544795] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB0) closing serial port...
modem-manager[1736]: <info>  [1359723717.545085] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB0) serial port closed
modem-manager[1736]: <debug> [1359723717.548011] [mm-modem-base.c:927] grab_port(): (ttyUSB0) type AT claimed by /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <info>  [1359723717.548630] [mm-manager.c:630] do_grab_port(): (Generic): GSM modem /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3 claimed port ttyUSB0
modem-manager[1736]: <debug> [1359723717.548960] [mm-manager.c:362] add_modem(): Added modem /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <debug> [1359723717.549246] [mm-manager.c:298] check_export_modem(): (tty/ttyUSB0): outstanding support task prevents export of /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <debug> [1359723717.549648] [mm-manager.c:298] check_export_modem(): (tty/ttyUSB1): outstanding support task prevents export of /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <debug> [1359723718.277202] [mm-manager.c:502] supports_defer_timeout(): (ttyUSB1): re-checking support...
modem-manager[1736]: <info>  [1359723718.278876] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB1) opening serial port...
modem-manager[1736]: <warn>  [1359723718.279090] [mm-serial-port.c:407] real_config_fd(): (ttyUSB1): port attributes not fully set
modem-manager[1736]: <debug> [1359723718.279208] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB1) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723718.279276] [mm-plugin-base.c:1064] try_open(): (ttyUSB1): probe requested by plugin 'Huawei'
modem-manager[1736]: <debug> [1359723718.280036] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR><LF>^BOOT:27285150,0,0,0,86<CR><LF><CR><LF>^SRVST:1<CR><LF><CR><LF>^MODE:5,4<CR><LF><CR><LF>^SIMST:1<CR><LF><CR><LF>^SRVST:2<CR><LF>'
modem-manager[1736]: <debug> [1359723718.295592] [mm-manager.c:502] supports_defer_timeout(): (ttyUSB3): re-checking support...
modem-manager[1736]: <info>  [1359723718.297071] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB3) opening serial port...
modem-manager[1736]: <warn>  [1359723718.297250] [mm-serial-port.c:407] real_config_fd(): (ttyUSB3): port attributes not fully set
modem-manager[1736]: <debug> [1359723718.297340] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB3) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723718.297406] [mm-plugin-base.c:1064] try_open(): (ttyUSB3): probe requested by plugin 'Huawei'
modem-manager[1736]: <debug> [1359723718.307137] [mm-manager.c:502] supports_defer_timeout(): (ttyUSB2): re-checking support...
modem-manager[1736]: <info>  [1359723718.308730] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB2) opening serial port...
modem-manager[1736]: <warn>  [1359723718.309373] [mm-serial-port.c:407] real_config_fd(): (ttyUSB2): port attributes not fully set
modem-manager[1736]: <debug> [1359723718.309850] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB2) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723718.310084] [mm-plugin-base.c:1064] try_open(): (ttyUSB2): probe requested by plugin 'Huawei'
modem-manager[1736]: <debug> [1359723718.380007] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723719.082923] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- 'AT+GCAP'
modem-manager[1736]: <debug> [1359723719.083276] [mm-at-serial-port.c:334] debug_log(): (ttyUSB3): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723719.083424] [mm-at-serial-port.c:334] debug_log(): (ttyUSB2): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723719.089397] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR>'
modem-manager[1736]: <debug> [1359723719.090515] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR><LF>+GCAP: +CGSM,+DS,+ES<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723719.090648] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): --> 'AT+CGMI<CR>'
modem-manager[1736]: <debug> [1359723719.794298] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- 'AT+CG<CR><LF>^RSSI:15<CR><LF>MI'
modem-manager[1736]: <debug> [1359723719.796272] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR>'
modem-manager[1736]: <debug> [1359723719.800768] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR><LF>huawei<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723719.801079] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): --> 'AT+CGMM<CR>'
modem-manager[1736]: <debug> [1359723720.501502] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- 'AT+CGMM'
modem-manager[1736]: <debug> [1359723720.502656] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR>'
modem-manager[1736]: <debug> [1359723720.503776] [mm-at-serial-port.c:334] debug_log(): (ttyUSB1): <-- '<CR><LF>E156G<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723720.504082] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB1) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723720.504295] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB1) closing serial port...
modem-manager[1736]: <info>  [1359723720.504645] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB1) serial port closed
modem-manager[1736]: <debug> [1359723720.505318] [mm-modem-base.c:927] grab_port(): (ttyUSB1) type AT claimed by /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <info>  [1359723720.505800] [mm-manager.c:630] do_grab_port(): (Huawei): GSM modem /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3 claimed port ttyUSB1
modem-manager[1736]: <debug> [1359723720.506082] [mm-manager.c:298] check_export_modem(): (tty/ttyUSB2): outstanding support task prevents export of /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <debug> [1359723723.150384] [mm-at-serial-port.c:334] debug_log(): (ttyUSB3): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723723.150558] [mm-at-serial-port.c:334] debug_log(): (ttyUSB2): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723727.150936] [mm-at-serial-port.c:334] debug_log(): (ttyUSB3): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723727.151077] [mm-at-serial-port.c:334] debug_log(): (ttyUSB2): --> 'AT+GCAP<CR>'
modem-manager[1736]: <debug> [1359723731.150378] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB3) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723731.150475] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB3) closing serial port...
modem-manager[1736]: <info>  [1359723731.150533] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB3) serial port closed
modem-manager[1736]: <info>  [1359723731.150672] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB3) opening serial port...
modem-manager[1736]: <debug> [1359723731.150839] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB3) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723731.150883] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB2) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723731.150906] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB2) closing serial port...
modem-manager[1736]: <info>  [1359723731.150942] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB2) serial port closed
modem-manager[1736]: <info>  [1359723731.151011] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB2) opening serial port...
modem-manager[1736]: <debug> [1359723731.151082] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB2) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723731.152217] [mm-qcdm-serial-port.c:196] debug_log(): (ttyUSB3): --> 7e 00 78 f0 7e
modem-manager[1736]: <debug> [1359723731.152343] [mm-qcdm-serial-port.c:196] debug_log(): (ttyUSB2): --> 7e 00 78 f0 7e
modem-manager[1736]: <debug> [1359723734.150573] [mm-qcdm-serial-port.c:196] debug_log(): (ttyUSB3): --> 7e 00 78 f0 7e
modem-manager[1736]: <debug> [1359723734.150740] [mm-qcdm-serial-port.c:196] debug_log(): (ttyUSB2): --> 7e 00 78 f0 7e
modem-manager[1736]: <debug> [1359723737.149857] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB3) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723737.149930] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB3) closing serial port...
modem-manager[1736]: <info>  [1359723737.149989] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB3) serial port closed
modem-manager[1736]: <debug> [1359723737.150247] [mm-manager.c:690] supports_callback(): (tty/ttyUSB3): ignoring port unsupported by physical modem's plugin
modem-manager[1736]: <debug> [1359723737.150289] [mm-manager.c:298] check_export_modem(): (tty/ttyUSB2): outstanding support task prevents export of /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3
modem-manager[1736]: <debug> [1359723737.150333] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB2) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723737.150360] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB2) closing serial port...
modem-manager[1736]: <info>  [1359723737.150396] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB2) serial port closed
modem-manager[1736]: <debug> [1359723737.150566] [mm-manager.c:690] supports_callback(): (tty/ttyUSB2): ignoring port unsupported by physical modem's plugin
modem-manager[1736]: <debug> [1359723737.150629] [mm-modem-base.c:208] log_port(): (/sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3) tty/ttyUSB0 primary
modem-manager[1736]: <debug> [1359723737.150651] [mm-modem-base.c:208] log_port(): (/sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3) tty/ttyUSB1 secondary
modem-manager[1736]: <debug> [1359723737.150672] [mm-modem-base.c:208] log_port(): (/sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3) tty/ttyUSB0 data
modem-manager[1736]: <info>  [1359723737.155830] [mm-serial-port.c:805] mm_serial_port_open(): (ttyUSB0) opening serial port...
modem-manager[1736]: <warn>  [1359723737.156072] [mm-serial-port.c:407] real_config_fd(): (ttyUSB0): port attributes not fully set
modem-manager[1736]: <debug> [1359723737.156196] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 1 (open)
modem-manager[1736]: <debug> [1359723737.156348] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 2 (open)
modem-manager[1736]: <debug> [1359723737.156460] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 3 (open)
modem-manager[1736]: <debug> [1359723737.157072] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 4 (open)
modem-manager[1736]: <debug> [1359723737.157290] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'ATE0<CR>'
modem-manager[1736]: <debug> [1359723737.162252] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- 'ATE0'
modem-manager[1736]: <debug> [1359723737.163107] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR>'
modem-manager[1736]: <debug> [1359723737.164108] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.164304] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+GMI<CR>'
modem-manager[1736]: <debug> [1359723737.172487] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>huawei<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.172584] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+GMM<CR>'
modem-manager[1736]: <debug> [1359723737.180484] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>E156G<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.180558] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+GMR<CR>'
modem-manager[1736]: <debug> [1359723737.188609] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>11.608.03.00.156<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.188818] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CGMI<CR>'
modem-manager[1736]: <debug> [1359723737.199310] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>huawei<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.199543] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CGMM<CR>'
modem-manager[1736]: <debug> [1359723737.208985] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>E156G<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.209080] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CGMR<CR>'
modem-manager[1736]: <debug> [1359723737.218001] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>11.608.03.00.156<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.218144] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'ATI<CR>'
modem-manager[1736]: <debug> [1359723737.223888] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>Manufacturer: huawei<CR><LF>Model: E156G<CR><LF>Revision: 11.608.03.00.156<CR><LF>IMEI: 358181027285150<CR><LF>+GCAP: +CGSM,+DS,+ES<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.224028] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'ATI1<CR>'
modem-manager[1736]: <debug> [1359723737.230880] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>Manufacturer: huawei<CR><LF>Model: E156G<CR><LF>Revision: 11.608.03.00.156<CR><LF>IMEI: 358181027285150<CR><LF>+GCAP: +CGSM,+DS,+ES<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.231008] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+GSN<CR>'
modem-manager[1736]: <debug> [1359723737.239877] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>358181027285150<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.240022] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CGSN<CR>'
modem-manager[1736]: <debug> [1359723737.249767] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>358181027285150<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.250028] [mm-modem-helpers.c:1069] mm_create_device_identifier(): Device ID source '000012d100001003Manufacturer:huaweiModel:E156GRevision:11.608.03.00.156IMEI:358181027285150+GCAP:+CGSM,+DS,+ES35818102728515011.608.03.00.156E156Ghuawei'
modem-manager[1736]: <debug> [1359723737.250055] [mm-modem-helpers.c:1070] mm_create_device_identifier(): Device ID 'd38d5edd4905a344e1d5ebc155c5cadc736da21d'
modem-manager[1736]: <debug> [1359723737.250132] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 3 (close)
modem-manager[1736]: <debug> [1359723737.250164] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'ATE0<CR>'
modem-manager[1736]: <debug> [1359723737.259145] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.259382] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 2 (close)
modem-manager[1736]: <debug> [1359723737.259410] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CMEE=1<CR>'
modem-manager[1736]: <debug> [1359723737.273394] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.273555] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CPIN?<CR>'
modem-manager[1736]: <debug> [1359723737.283630] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CPIN: READY<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.283819] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 3 (open)
modem-manager[1736]: <debug> [1359723737.283861] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 2 (close)
modem-manager[1736]: <debug> [1359723737.283888] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK=?<CR>'
modem-manager[1736]: <debug> [1359723737.295133] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: ("AB","AC","AG","AI","AO","IR","OI","OX","SC","FD","PN","PU","PP","PC","PF")<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.295376] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 3 (open)
modem-manager[1736]: <debug> [1359723737.295413] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 4 (open)
modem-manager[1736]: <debug> [1359723737.295439] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 5 (open)
modem-manager[1736]: <debug> [1359723737.295464] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 6 (open)
modem-manager[1736]: <debug> [1359723737.295487] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 7 (open)
modem-manager[1736]: <debug> [1359723737.295511] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 8 (open)
modem-manager[1736]: <debug> [1359723737.295536] [mm-serial-port.c:874] mm_serial_port_open(): (ttyUSB0) device open count is 9 (open)
modem-manager[1736]: <debug> [1359723737.295561] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 8 (close)
modem-manager[1736]: <debug> [1359723737.295608] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CRSM=176,12258,0,0,10<CR>'
modem-manager[1736]: <debug> [1359723737.357256] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CRSM: 144,0,"989399240810649887F7"<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.357485] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 7 (close)
modem-manager[1736]: <debug> [1359723737.357582] [mm-generic-gsm.c:515] get_iccid_done(): SIM ID source '8939994280014689787'
modem-manager[1736]: <debug> [1359723737.357610] [mm-generic-gsm.c:516] get_iccid_done(): SIM ID '45d7089ca668ede51d440635ab563f4a28c0977b'
modem-manager[1736]: <debug> [1359723737.357951] [mm-manager.c:313] check_export_modem(): Exported modem /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-3 as /org/freedesktop/ModemManager/Modems/0
modem-manager[1736]: <debug> [1359723737.358083] [mm-manager.c:327] check_export_modem(): (/org/freedesktop/ModemManager/Modems/0): VID 0x12D1 PID 0x1003 (usb)
modem-manager[1736]: <debug> [1359723737.358111] [mm-manager.c:328] check_export_modem(): (/org/freedesktop/ModemManager/Modems/0): data port is ttyUSB0
modem-manager[1736]: <debug> [1359723737.361286] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="SC",2<CR>'
modem-manager[1736]: <debug> [1359723737.387270] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.387512] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 6 (close)
modem-manager[1736]: <debug> [1359723737.387570] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="FD",2<CR>'
modem-manager[1736]: <debug> [1359723737.405003] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.405212] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 5 (close)
modem-manager[1736]: <debug> [1359723737.405266] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="PF",2<CR>'
modem-manager[1736]: <debug> [1359723737.431918] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.432082] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 4 (close)
modem-manager[1736]: <debug> [1359723737.432140] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="PN",2<CR>'
modem-manager[1736]: <debug> [1359723737.454362] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.454622] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 3 (close)
modem-manager[1736]: <debug> [1359723737.454692] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="PU",2<CR>'
modem-manager[1736]: <debug> [1359723737.476389] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.476610] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 2 (close)
modem-manager[1736]: <debug> [1359723737.476675] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="PP",2<CR>'
modem-manager[1736]: <debug> [1359723737.498265] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.498501] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 1 (close)
modem-manager[1736]: <debug> [1359723737.498560] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+CLCK="PC",2<CR>'
modem-manager[1736]: <debug> [1359723737.523970] [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '<CR><LF>+CLCK: 0<CR><LF><CR><LF>OK<CR><LF>'
modem-manager[1736]: <debug> [1359723737.524173] [mm-serial-port.c:908] mm_serial_port_close(): (ttyUSB0) device open count is 0 (close)
modem-manager[1736]: <info>  [1359723737.524209] [mm-serial-port.c:923] mm_serial_port_close(): (ttyUSB0) closing serial port...
modem-manager[1736]: <info>  [1359723737.524557] [mm-serial-port.c:944] mm_serial_port_close(): (ttyUSB0) serial port closed

*** Start NetworkManager again:
$ sudo NM_PPP_DEBUG=1 /usr/sbin/NetworkManager --no-daemon

NetworkManager logs:

NetworkManager[1838]: <info> NetworkManager (version 0.9.4.0) is starting...
NetworkManager[1838]: <info> Read config file /etc/NetworkManager/NetworkManager.conf
NetworkManager[1838]: <info> VPN: loaded org.freedesktop.NetworkManager.pptp
NetworkManager[1838]: <info> DNS: loaded plugin dnsmasq
NetworkManager[1838]:    SCPlugin-Ifupdown: init!
NetworkManager[1838]:    SCPlugin-Ifupdown: update_system_hostname
NetworkManager[1838]:    SCPluginIfupdown: management mode: unmanaged
NetworkManager[1838]:    SCPlugin-Ifupdown: devices added (path: /sys/devices/pci0000:00/0000:00:1e.0/0000:02:00.0/net/eth0, iface: eth0)
NetworkManager[1838]:    SCPlugin-Ifupdown: device added (path: /sys/devices/pci0000:00/0000:00:1e.0/0000:02:00.0/net/eth0, iface: eth0): no ifupdown configuration found.
NetworkManager[1838]:    SCPlugin-Ifupdown: devices added (path: /sys/devices/pci0000:00/0000:00:1e.0/0000:02:06.0/net/eth1, iface: eth1)
NetworkManager[1838]:    SCPlugin-Ifupdown: device added (path: /sys/devices/pci0000:00/0000:00:1e.0/0000:02:06.0/net/eth1, iface: eth1): no ifupdown configuration found.
NetworkManager[1838]:    SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/lo, iface: lo)
NetworkManager[1838]:    SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/lo, iface: lo): no ifupdown configuration found.
NetworkManager[1838]:    SCPlugin-Ifupdown: end _init.
NetworkManager[1838]: <info> Loaded plugin ifupdown: (C) 2008 Canonical Ltd.  To report bugs please use the NetworkManager mailing list.
NetworkManager[1838]: <info> Loaded plugin keyfile: (c) 2007 - 2010 Red Hat, Inc.  To report bugs please use the NetworkManager mailing list.
NetworkManager[1838]:    Ifupdown: get unmanaged devices count: 0
NetworkManager[1838]:    SCPlugin-Ifupdown: (165154152) ... get_connections.
NetworkManager[1838]:    SCPlugin-Ifupdown: (165154152) ... get_connections (managed=false): return empty list.
NetworkManager[1838]:    keyfile: parsing Cablata su eth0 ... 
NetworkManager[1838]:    keyfile:     read connection 'Cablata su eth0'
NetworkManager[1838]:    keyfile: parsing TPLink - Ufficio ... 
NetworkManager[1838]:    keyfile:     read connection 'TPLink - Ufficio'
NetworkManager[1838]:    keyfile: parsing GreenSpirit ... 
NetworkManager[1838]:    keyfile:     read connection 'GreenSpirit'
NetworkManager[1838]:    keyfile: parsing Vodafone - Ricky ... 
NetworkManager[1838]:    keyfile:     read connection 'Vodafone - Ricky'
NetworkManager[1838]:    keyfile: parsing PurpleSpirit ... 
NetworkManager[1838]:    keyfile:     read connection 'PurpleSpirit'
NetworkManager[1838]:    keyfile: parsing 3 - Ricaricabile ... 
NetworkManager[1838]:    keyfile:     read connection '3 - Ricaricabile'
NetworkManager[1838]:    Ifupdown: get unmanaged devices count: 0
NetworkManager[1838]: <info> modem-manager is now available
NetworkManager[1838]: <info> monitoring kernel firmware directory '/lib/firmware'.
NetworkManager[1838]: <info> found WiFi radio killswitch rfkill0 (at /sys/devices/pci0000:00/0000:00:1e.0/0000:02:06.0/ieee80211/phy0/rfkill0) (driver (unknown))
NetworkManager[1838]: <info> WiFi disabled by radio killswitch; enabled by state file
NetworkManager[1838]: <info> WWAN enabled by radio killswitch; enabled by state file
NetworkManager[1838]: <info> WiMAX enabled by radio killswitch; enabled by state file                                                                                               
NetworkManager[1838]: <info> Networking is enabled by state file                                                                                                                    
NetworkManager[1838]: <warn> failed to allocate link cache: (-10) Operation not supported                                                                                           
NetworkManager[1838]: <info> (eth0): carrier is OFF                                                                                                                                 
NetworkManager[1838]: <info> (eth0): new Ethernet device (driver: '8139too' ifindex: 2)
NetworkManager[1838]: <info> (eth0): exported as /org/freedesktop/NetworkManager/Devices/0
NetworkManager[1838]: <info> (eth0): now managed
NetworkManager[1838]: <info> (eth0): device state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
NetworkManager[1838]: <info> (eth0): bringing up device.
NetworkManager[1838]: <info> (eth0): preparing device.
NetworkManager[1838]: <info> (eth0): deactivating device (reason 'managed') [2]
NetworkManager[1838]: <info> (eth1): driver supports SSID scans (scan_capa 0x21).
NetworkManager[1838]: <info> (eth1): using WEXT for WiFi device control
NetworkManager[1838]: <info> (eth1): new 802.11 WiFi device (driver: 'ipw2200' ifindex: 3)
NetworkManager[1838]: <info> (eth1): exported as /org/freedesktop/NetworkManager/Devices/1
NetworkManager[1838]: <info> (eth1): now managed
NetworkManager[1838]: <info> (eth1): device state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
NetworkManager[1838]: <info> (eth1): bringing up device.
NetworkManager[1838]: <info> (eth1): deactivating device (reason 'managed') [2]
/sbin/ifup: interface lo already configured

*** After plugin, when the device can work, NetworkManager logs:

NetworkManager[1838]: <info> the modem manager disappeared
NetworkManager[1838]: <info> trying to start the modem manager...
NetworkManager[1838]: <info> modem-manager is now available
NetworkManager[1838]: <warn> (ttyUSB0): failed to look up interface index
NetworkManager[1838]: <info> (ttyUSB0): new GSM/UMTS device (driver: 'generic' ifindex: 0)
NetworkManager[1838]: <info> (ttyUSB0): exported as /org/freedesktop/NetworkManager/Devices/2
NetworkManager[1838]: <info> (ttyUSB0): now managed
NetworkManager[1838]: <info> (ttyUSB0): device state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
NetworkManager[1838]: <info> (ttyUSB0): deactivating device (reason 'managed') [2]
NetworkManager[1838]: nm_system_iface_flush_routes: assertion `ifindex > 0' failed
NetworkManager[1838]: nm_system_iface_flush_addresses: assertion `ifindex > 0' failed
NetworkManager[1838]: <info> (ttyUSB0): device state change: unavailable -> disconnected (reason 'none') [20 30 0]

--- or, when the modemmanager logs are more verbose (see above trace), the logs could be ---

NetworkManager[1742]: <warn> (ttyUSB0): failed to look up interface index
NetworkManager[1742]: <info> (ttyUSB0): new GSM/UMTS device (driver: 'generic' ifindex: 0)
NetworkManager[1742]: <info> (ttyUSB0): exported as /org/freedesktop/NetworkManager/Devices/2
NetworkManager[1742]: <info> (ttyUSB0): now managed
NetworkManager[1742]: <info> (ttyUSB0): device state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
NetworkManager[1742]: <info> (ttyUSB0): deactivating device (reason 'managed') [2]
NetworkManager[1742]: nm_system_iface_flush_routes: assertion `ifindex > 0' failed
NetworkManager[1742]: nm_system_iface_flush_addresses: assertion `ifindex > 0' failed
NetworkManager[1742]: <info> (ttyUSB0): device state change: unavailable -> disconnected (reason 'none') [20 30 0]

then the modem becomes available again (and could connect).

*** The output of the 'dmesg' command from around the time I've experienced the problem:

$ dmesg | tail
[21417.584792] usbserial_generic 1-3:1.0: device disconnected
[21423.776074] usb 1-3: new high-speed USB device number 3 using ehci_hcd
[21423.924183] usbserial_generic 1-3:1.0: generic converter detected
[21423.924411] usb 1-3: generic converter now attached to ttyUSB0
[21423.924721] usbserial_generic 1-3:1.1: generic converter detected
[21423.924925] usb 1-3: generic converter now attached to ttyUSB1
[21423.925185] usbserial_generic 1-3:1.2: generic converter detected
[21423.925385] usb 1-3: generic converter now attached to ttyUSB2
[21423.925632] usbserial_generic 1-3:1.3: generic converter detected
[21423.925968] usb 1-3: generic converter now attached to ttyUSB3

Log File Locations, NetworkManager (Kubuntu 12.04): /var/log/syslog

*** Grabbed NetworkManager.log with:
$ grep -i networkmanager /var/log/syslog > ~/NetworkManager.log

*** Grabbed ModemManager.log with:
$ grep -i modem-manager /var/log/syslog > ~/ModemManager.log

***************
$ lsusb -v:
Bus 001 Device 004: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E230/E270/E870 HSDPA/HSUPA Modem
Couldn't open device, some information will be missing
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x12d1 Huawei Technologies Co., Ltd.
  idProduct          0x1003 E220 HSDPA Modem / E230/E270/E870 HSDPA/HSUPA Modem
  bcdDevice            0.00
  iManufacturer           2 
  iProduct                1 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          108
    bNumInterfaces          4
    bConfigurationValue     1
    iConfiguration          3 
    bmAttributes         0xe0
      Self Powered
      Remote Wakeup
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               5
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval              32
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval              32
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval              32
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval              32
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     80 Bulk-Only
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x03  EP 3 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        3
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     80 Bulk-Only
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x04  EP 4 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
        
*** end of the report ***