At the end of a PPP connection, garbage was passed in to the AT command
parser on the modem chat.
Well, the modem should not be passing in garbage in the first place :)
This garbage contained a doublequote, which switched the AT syntax
parser into string mode.
However, because no second doublequote arrived, it stayed in this mode,
and kept returning UNSURE result.
Do you have a trace/hexdump of what is passed on to the GAtChat object?
I think this is an major issue that should be fixed in oFono.
The syntax parser has to be extended to handle such cases.
Any suggestions on how oFono should detect this condition?