I'm experiencing this bug as well, with one small but important difference: the "hit and miss" behaviour Rishi describes was already present with 11.10/Oneiric on my machine, and after upgrading to 12.04/Precise, the modem doesn't work at all. The kernel detects it when I plug it in, then flip-flops between "storage device" and "modem" for a while (during which the computer freezes for >10 seconds several times), but nothing else happens. NetworkManager cannot "see" the modem.
I'm experiencing this bug as well, with one small but important difference: the "hit and miss" behaviour Rishi describes was already present with 11.10/Oneiric on my machine, and after upgrading to 12.04/Precise, the modem doesn't work at all. The kernel detects it when I plug it in, then flip-flops between "storage device" and "modem" for a while (during which the computer freezes for >10 seconds several times), but nothing else happens. NetworkManager cannot "see" the modem.
Pertinent syslog excerpt attached.