Comment 110 for bug 868034

Aleksander: I have installed modem-manager 0.4 on my 11.10 system and it works ok - a debug log is attached (it contains the sequence connect/disconnect/connect)

It was quite painless for me to install the older release, so this might be a suitable interim solution for some other people who are having this problem.

To install the version from Natty you need to:

Step 1:
Fetch the old .deb file. You can get this from:
http://packages.ubuntu.com/natty/modemmanager
In the section "Download modemmanager" click on either amd64 or i386 as appropriate for your machine and save the file somewhere.

I'm using 64-bit so the file I retrieved is called:
modemmanager_0.4+git.20110124t203624.00b6cce-2ubuntu1_amd64.deb

Step 2:
Remove the current (broken) version of modemmanager from your machine.
sudo dpkg --purge modemmanager

Step 3:
Install the older version that you downloaded in Step 1.
sudo dpkg -i modemmanager_0.4+git.20110124t203624.00b6cce-2ubuntu1_amd64.deb

Step 4:
(not 100% sure this is needed but won't hurt)
Bounce the NetworkManager
sudo stop network-manager
sudo start network-manager

The modem should now work as it did in 11.04.

You might want to perform an additional step to prevent the update manager from reinstalling the broken version:

Optional Step 5:
Start the Synaptic Package Manager
Find modemmanager in the packages list. It should look something like:
S | | Package | Installed Version | Latest Version | Description
! modemmanager | 0.4+git.20110124t203624.00b6cce-2ubuntu1| 0.5-1ubuntu1 | D-Bus service for managing modems

Click on the modemmanager package, then from the menu select Package -> Lock Version

Obviously at some future time when this bug is fixed you will want to unlock this version by again selecting Package -> Lock Version