network manager doesn't see mobile networks on battery power

[bryncoles]

When using Xubuntu 12.04 on battery power, i have just realised that I cannot connect to the mobile internet.

Expected behaviour: plug in (Nokia) mobile phone -- select 'pc suite' as connection type. Click network manager in task-bar. Select mobile broadband connection. Connect to internet.

Observed behaviour: plug in (Nokia) mobile phone -- select 'pc suite' as connection type. Click network manager in task-bar. See that not mobile network is available. Do not connect to internet(!)

Requested details follow.

$ lsb_release -rd
Description: Ubuntu 12.04 LTS
Release: 12.04

$ apt-cache policy network-manager
network-manager:
  Installed: 0.9.4.0-0ubuntu4
  Candidate: 0.9.4.0-0ubuntu4
  Version table:
 *** 0.9.4.0-0ubuntu4 0
        500 http://gb.archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     0.9.4.0-0ubuntu3 0
        500 http://gb.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: network-manager 0.9.4.0-0ubuntu4
ProcVersionSignature: Ubuntu 3.2.0-24.39-generic 3.2.16
Uname: Linux 3.2.0-24-generic x86_64
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
Date: Sun May 27 17:00:41 2012
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationMedia: Xubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
IpRoute:
 default via 10.6.6.6 dev ppp0 proto static
 10.6.6.6 dev ppp0 proto kernel scope link src 10.165.201.200
 169.254.0.0/16 dev ppp0 scope link metric 1000
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: network-manager
UpgradeStatus: Upgraded to precise on 2012-05-04 (23 days ago)
nmcli-con:
 NAME UUID TYPE TIMESTAMP TIMESTAMP-REAL AUTOCONNECT READONLY DBUS-PATH
 Wired connection 1 93fd1be1-2e0d-4d12-abe8-ddb42ecbd457 802-3-ethernet 1338113409 Sun 27 May 2012 11:10:09 BST no no /org/freedesktop/NetworkManager/Settings/2
 eduroam a3128d87-f057-4d70-8abf-9392a4049ca1 802-11-wireless 1330424231 Tue 28 Feb 2012 10:17:11 GMT no no /org/freedesktop/NetworkManager/Settings/1
 T-Mobile Default e2e62a31-ada0-4564-b4c7-dd53e3d92964 gsm 1338134318 Sun 27 May 2012 16:58:38 BST no no /org/freedesktop/NetworkManager/Settings/0
 lancaster a8b96bc0-181f-4934-8970-6ea88204622c 802-11-wireless 0 never yes no /org/freedesktop/NetworkManager/Settings/3
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 ttyACM0 gsm connected /org/freedesktop/NetworkManager/Devices/2
 wlan0 802-11-wireless unavailable /org/freedesktop/NetworkManager/Devices/1
 eth0 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.4.0 connected enabled disabled disabled enabled enabled