Data call (aka CSD) with QtExtended

Mile Davidovic david.moko.comunity at gmail.com
Thu May 7 09:14:22 CEST 2009


Yes, nice explanation. CSD is used as preferable scenario for transporting
crypted voice.
Regards
Mile


On Wed, May 6, 2009 at 12:31 AM, Al Johnson
<openmoko at mazikeen.demon.co.uk>wrote:

> On Tuesday 05 May 2009, Franky Van Liedekerke wrote:
> > On Tue, 5 May 2009 22:44:49 +0200
> >
> > Mile Davidovic <david.moko.comunity at gmail.com> wrote:
> > > Hello
> > >
> > > My understanding is next:
> > > - qt extended have support for CSD but quite rudimentary (these words
> > > are from qt extended documentation)
> > > - sample qt application works fine with CSD but only first time (they
> > > have problem with releasing resources)
> > >
> > > In general, OpenMoko is capable of working with CSD but my
> > > understanding is that CSD (at least on Qt) is not preferable working
> > > scenario.
> > >
> > > Regards
> > > Mile
> >
> > Hi Mile,
> >
> > I'm sorry, but I'm not really familiar with CSD calls, could you
> > ellaborate?
>
> Circuit Switched Data, the original GSM data mode where the phone acts as a
> slow (9600) conventional modem. Later HSCSD increased the speed a bit by
> channel bonding. My k700i will let you select between analogue and ISDN
> modem
> behaviour, handy when calling an ISDN line as it doesn't need all the time
> consuming analogue negotiation when it connects.
>
> In theory it should be really simple to use; just configure ppp as if you
> were
> connecting to a serial modem. gsm0710muxd or equivalent may complicate this
> slightly, but I wouldn't expect it to be any worse than the current use of
> ppp
> for GPRS. That said, I haven't tried it.
>
> While GPRS is faster CSD has other advantages which may be critical in some
> cases. You can call into it, which may not be possible with GPRS as it is
> often hidden behind NAT. CDS also has lower, predictable latency whch made
> it
> the transport of choice for a GSM cryptophone.
>
>
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