Update: reading the changelog I found "debian/README.Debian: adapt README to match the new behaviour of network-manager, which doesn't manage _any_ device configured in /etc/network/interfaces anymore."
Anyway, it seems that this is the actual bug, not being able to bring up the contextual menu for dialup once a static IP is defined: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/5364
Update: reading the changelog I found "debian/ README. Debian: adapt README to match the new behaviour of network-manager, which doesn't manage _any_ device configured in /etc/network/ interfaces anymore."
Anyway, it seems that this is the actual bug, not being able to bring up the contextual menu for dialup once a static IP is defined: https:/ /bugs.launchpad .net/ubuntu/ +source/ network- manager/ +bug/5364