I discovered a problem in my earlier test: there was still a modem-manager binary used from /usr/local/sbin. Hence the testing proofed nothing. However, a new test revealed that the current Lucid mm works with the old Karmic nm:
network-manager: 0.8~rc1-0ubuntu1~nmt1~karmic modemmanager: 0.3-0ubuntu2
My current hypothesis is that something broke in network-manager.
I discovered a problem in my earlier test: there was still a modem-manager binary used from /usr/local/sbin. Hence the testing proofed nothing. However, a new test revealed that the current Lucid mm works with the old Karmic nm:
network-manager: 0.8~rc1- 0ubuntu1~ nmt1~karmic
modemmanager: 0.3-0ubuntu2
My current hypothesis is that something broke in network-manager.