Mobile Broadband Modem disconnects, disappears from NetworkManager list

[kiran]

i use a mobile broadband connection in Ubuntu. i connect it to my notebook via blue tooth of mobile phone.while using internet mobile broadband modem just disconnects and disappears from the network indicator in the status bar

also my connection is not listed in the network connection>mobile broadband tab

similar bug is reported before Bug #869954 in that case Mobile Broadband Modem is connected using usb i also face that problem

what i do to get back moblie internet connection name in the networkmanager list is, open the Bluetooth settings select my mobile as i tick "use your mobile as network device(PAN/NAP)" option moblie internet connection comes back in the network list

syslog file

May 18 18:17:01 kiru-Lenovo-G580 CRON[19997]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
May 18 18:19:19 kiru-Lenovo-G580 pppd[7228]: Modem hangup
May 18 18:19:19 kiru-Lenovo-G580 pppd[7228]: Connect time 40.1 minutes.
May 18 18:19:19 kiru-Lenovo-G580 pppd[7228]: Sent 823635 bytes, received 2659494 bytes.
May 18 18:19:19 kiru-Lenovo-G580 pppd[7228]: Connection terminated.
May 18 18:19:19 kiru-Lenovo-G580 avahi-daemon[1086]: Withdrawing workstation service for ppp0.
May 18 18:19:19 kiru-Lenovo-G580 dbus[997]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
May 18 18:19:19 kiru-Lenovo-G580 dbus[997]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
May 18 18:19:19 kiru-Lenovo-G580 dnsmasq[7245]: exiting on receipt of SIGTERM
May 18 18:19:19 kiru-Lenovo-G580 dnsmasq[20632]: started, version 2.59 cache disabled
May 18 18:19:19 kiru-Lenovo-G580 dnsmasq[20632]: compile time options: IPv6 GNU-getopt DBus i18n DHCP TFTP conntrack IDN
May 18 18:19:19 kiru-Lenovo-G580 dnsmasq[20632]: warning: no upstream servers configured
May 18 18:19:21 kiru-Lenovo-G580 pppd[7228]: Exit.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: network-manager-gnome 0.9.4.1-0ubuntu2.1
ProcVersionSignature: Ubuntu 3.5.0-26.42~precise1-generic 3.5.7.6
Uname: Linux 3.5.0-26-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: amd64
Date: Sat May 18 18:51:47 2013
ExecutablePath: /usr/bin/nm-connection-editor
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
IpRoute:

MarkForUpload: True
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
ProcEnviron:
 LANGUAGE=en_IN:en
 PATH=(custom, no user)
 LANG=en_IN
 SHELL=/bin/bash
SourcePackage: network-manager-applet
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 D4:C1:FC:AB:2D:B2 bluetooth disconnected /org/freedesktop/NetworkManager/Devices/6
 eth1 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/1
 eth0 802-11-wireless disconnected /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.4.0 disconnected enabled enabled enabled enabled enabled