Dialup disabled by Network Manager when I connect ethernet/wireless

[Shriramana Sharma <samjnaa gmail com>]

Reposting to this list from: 
http://ubuntuforums.org/showthread.php?t=1790528

Hello. I'm running Kubuntu Natty. As I have no broadband connection at 
home [:(] I have to connect to the net via my Nokia C5 mobile phone and 
a Vodafone 2G connection. Thankfully Natty automatically detects my 
phone when it is plugged in in the correct mode and using a wizard 
enables me to connect.

However, I also have an ethernet/wireless router connecting my two 
laptops and desktop via ethernet cable.

The problem is that when I connect to my local home network via ethernet 
or wireless, the dialup mobile internet connection gets disabled. See 
the below behaviour when I disconnect and then reconnect my ethernet 
(similar thing happens for wireless too):

$ dmesg | tail
[   21.364609] NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state 
recovery directory
[   21.377712] NFSD: starting 90-second grace period
[   22.383233] acer_wmi: Acer Laptop WMI Extras unloaded
[   28.389718] PPP BSD Compression module registered
[   28.429614] PPP Deflate Compression module registered
[  232.247075] r8169 0000:03:00.0: eth0: link up
[  232.247730] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[  242.382351] eth0: no IPv6 routers present
[  329.914179] r8169 0000:03:00.0: eth0: link down
[  340.164564] r8169 0000:03:00.0: eth0: link up
$ tail /var/log/syslog
Jun 25 09:53:52 sarvajnatma NetworkManager[873]: <info> Scheduling stage 5
Jun 25 09:53:52 sarvajnatma NetworkManager[873]: <info> Activation 
(eth0) Stage 5 of 5 (IP Configure Commit) scheduled...
Jun 25 09:53:52 sarvajnatma NetworkManager[873]: <info> Done scheduling 
stage 5
Jun 25 09:53:52 sarvajnatma NetworkManager[873]: <info> Activation 
(eth0) Stage 4 of 5 (IP4 Configure Get) complete.
Jun 25 09:53:52 sarvajnatma NetworkManager[873]: <info> Activation 
(eth0) Stage 5 of 5 (IP Configure Commit) started...
Jun 25 09:53:53 sarvajnatma NetworkManager[873]: <info> Policy set 
'Vodafone - Vodafone Connect' (ppp0) as default for IPv4 routing and DNS.
Jun 25 09:53:53 sarvajnatma NetworkManager[873]: <info> (eth0): device 
state change: 7 -> 8 (reason 0)
Jun 25 09:53:53 sarvajnatma NetworkManager[873]: <info> Policy set 'Auto 
eth0' (eth0) as default for IPv4 routing and DNS.
Jun 25 09:53:53 sarvajnatma NetworkManager[873]: <info> Activation 
(eth0) successful, device activated.
Jun 25 09:53:53 sarvajnatma NetworkManager[873]: <info> Activation 
(eth0) Stage 5 of 5 (IP Configure Commit) complete.

The problem is evident in the line that says that the policy has been 
changed to choose the ethernet connection for IP4 routing and DNS when 
it is plugged in, probably because NM assumes that ethernet would give 
greater speeds than dialup. The problem is that my ethernet (and 
wireless) isn't connected to the internet at all but only the dialup is!

On the Kubuntu NM tray applet I find no option by which to change the 
default for IP4 routing and DNS back to my mobile internet connection.

Can anyone please help?

--
Shriramana Sharma