how to get 3g modem back in managed state

[Eduard Hasenleithner <ehasenle gmail com>]

I'm using network-manager on ubuntu oneiric. Every time the modem gets
disconnected (either by the network, or due to bad reception) it
disappears from the network device list.

Dec 29 18:17:28 eeepc pppd[2070]: LCP terminated by peer
Dec 29 18:17:28 eeepc pppd[2070]: Connect time 1.4 minutes.
Dec 29 18:17:28 eeepc pppd[2070]: Sent 47182 bytes, received 339954 bytes.
Dec 29 18:17:28 eeepc charon: 08[KNL] interface ppp0 deactivated
Dec 29 18:17:28 eeepc charon: 08[KNL] 10.61.6.235 disappeared from ppp0
Dec 29 18:17:28 eeepc pppd[2070]: Modem hangup
Dec 29 18:17:28 eeepc pppd[2070]: Connection terminated.
Dec 29 18:17:28 eeepc NetworkManager[666]: <info> (ttyUSB0): device
state change: activated -> failed (reason 'ppp-disconnect') [100 120
13]
Dec 29 18:17:28 eeepc NetworkManager[666]: <warn> Activation (ttyUSB0) failed.
Dec 29 18:17:28 eeepc avahi-daemon[526]: Withdrawing workstation
service for ppp0.
Dec 29 18:17:28 eeepc modem-manager[519]: <info>  (ttyUSB0) closing
serial port...
Dec 29 18:17:28 eeepc modem-manager[519]: <info>  (ttyUSB0) serial port closed
Dec 29 18:17:28 eeepc modem-manager[519]: <info>  Modem
/org/freedesktop/ModemManager/Modems/0: state changed (connected ->
disconnecting)
Dec 29 18:17:28 eeepc modem-manager[519]: <info>  Modem
/org/freedesktop/ModemManager/Modems/0: state changed (disconnecting
-> connected)
Dec 29 18:17:28 eeepc NetworkManager[666]:    SCPlugin-Ifupdown:
devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
Dec 29 18:17:28 eeepc NetworkManager[666]: <info> (ttyUSB0): now unmanaged
Dec 29 18:17:28 eeepc NetworkManager[666]: <info> (ttyUSB0): device
state change: failed -> unmanaged (reason 'removed') [120 10 36]
Dec 29 18:17:28 eeepc NetworkManager[666]: <info> (ttyUSB0):
deactivating device (reason 'removed') [36]
Dec 29 18:17:28 eeepc dbus[488]: [system] Activating service
name='org.freedesktop.nm_dispatcher' (using servicehelper)
Dec 29 18:17:28 eeepc NetworkManager[666]: <warn> could not read ppp
stats: No such device

Is there a way to get it back without a reboot?