[Gta04-owner] Detect Call Hangup / Option Datasheet

Marcel Holtmann marcel at holtmann.org
Mon Jan 2 02:45:57 CET 2012

Hi Nikolaus,

> > > That is why every serious voice modem manufacturer adds a vendor command
> > > for call state notifications. And more important why they make ATD123; a
> > > non blocking call where OK is returned right away. However it seems that
> > > nobody told this to Option. Polling via CLCC is still nasty, but doable,
> > > but having a blocking ATD123; is just pure stupid.
> > 
> > I think it does not block if AT+COLP=0
> I can try that later with one of my other Option cards, but this is
> kinda weird as well. Since we want to have AT+COLP=1 to get unsolicited
> connected line identification.

so I took one of my Option cards and indeed if you set AT+COLP=0 then
the ATD123; returns OK right away. So far so good.

While someone could argue that this is the expected behavior according
to 27.007, I still think this is kinda stupid and should be addressed
with Option. It would be enough to just add a AT_OCOLP=1 vendor command
or something similar to get the behavior of COLP=1 and non-blocking ATD
for voice calls. In case Option insists on keeping this weird behavior.

I continued testing and the other major problem with Option now is that
their voice implementation does not send NO CARRIER, NO ANSWER or BUSY
as feedback from the remote party.

This means that during an active call you have to poll with AT+CLCC to
check for remote party hangup. Even the strict 27.007 voice call support
in oFono assumes at least that you have these unsolicited notification
coming from the modem. This should be something that you might wanna
address with Option as well. We can get oFono support for this, but this
is a serious power drainer (especially on USB) during an active voice



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