[Gta04-owner] Modem crashing?

Marcel Holtmann marcel at holtmann.org
Thu Feb 16 08:37:23 CET 2012

Hi Nikolaus,

> >>> start it with "env OFONO_AT_DEBUG=1 ofonod -n -d" and you even get the
> >>> AT command traces.
> >> 
> >> Below are two oFono logs from me.  In the first one, note that there is
> >> an error with the CLCC polling:
> >> 
> >> ofonod[923]: App: < \r\n+CME ERROR: 100\r\n
> >> ofonod[923]: We are polling CLCC and received an error
> > 
> > this indicates an "Unknown error". Nothing we can do. I can just only
> > say it again, this Option modem is not a voice call modem. For voice
> > calls it is a pretty poor choice.
> Why should they implement and certify voice commands, PCM audio
> interface and so on if it were a data call only modem?

either they have a call state notification command and never told you
about it or this modem has never been used for voice calls.

If anybody would have been serious about using this in a phone type
device with voice calls, then a call state notification would exist. The
polling is expensive and will drain your battery. In addition doing that
on USB is not really battery friendly either.

The underlying Qualcomm firmware actually does support the voice call
handling, but it only implements the 27.007 specification. Qualcomm has
been known to not expose anything extra on their AT command support.
They want you to use QMI or other protocols. If you want special AT
commands, then vendors like Option, Huawei, ZTE etc. have to implement

Look at Huawei for example, they ended up using their specific voice
call notifications they used in their CDMA modems.

> > We even tell you that all bets are off now ;)
> > 
> > ofonod[923]: App: < \r\n+CME ERROR: 100\r\n
> > ofonod[923]: We are polling CLCC and received an error
> > ofonod[923]: All bets are off for call management
> > 
> >> The consequence of that is that when I cancel the call attempt, on the
> >> calling phone, oFono doesn't detect that, and so my UI still shows the
> >> incoming call.
> > 
> > Other real voice call capable modems have an unsolicited notification
> > for call state changes or at least send NO CARRIER. This modem has
> > neither and is pretty bad.
> I have forwarded this issue to OPTION why we don't see the NO CARRIER
> as recommended by GSM07.07 appendix f and g. Let's see their answer.

You are trying to workaround something here that is fundamentally
broken. The 27.007 specification for voice call handling is useless.
Every single modem manufacturer that ever had their modem put into a
phone has realized this.

You need Option to ask to add proper voice call handling commands and
that is having a unsolicited notification for call state changes.



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