Hi,
Thanks for help, but ModemManager doesn't seem to be an issue. Question: Does "Cannot open serial device /dev/ttyUSB0" error mean that it is unable to connect to my USB adapter or that there might not be a phone connected on the other end of the adapter?
It means it can't open the char device ... basically the call to open("/dev/ttyUSB0") failed somehow. nothing to do with the phone.
Cheers,
Sylvain