Hi Bo,

 > The man pages mention that:
>
> "oFono is controlled through D-Bus;
> for example, one can tell ofonod to send
> AT commands over /dev/rfcomm0 by calling
> the D-Bus method org.ofono.at.Manager.Create"

Well this is embarrassing.  That manpage is completely out of date. 
Please forget whatever you read in it.

USB Modem detection in oFono is handled by plugins/udevng.c.  Generally, 
things just work.  However, you might have a device that isn't 
supported.  At least the vendor id / product id you mention are missing 
from udevng.c.

Regards,
-Denis