Always-on networking via GPRS

Bjarne Vestergaard bjvest at
Mon May 7 22:02:11 CEST 2007

As far as I recall, GPRS relies on something called a PDP context to carry 
information like the IP address of the handset. When a call comes in, the 
GPRS service is temporarily disabled, but the PDP context need not be 
destroyed. Or, more precisely, the handset implementation _could_ be made to 
let the PDP context survive. When the voice call is terminated again and the 
GPRS service is reactivated, the PDP context can therefore be reused. Hence, 
the handset IP address will not change in this case.

Best regards,

On Tuesday 01 May 2007 19:55:45 Tim Newsom wrote:
> On Tue, 1 May 2007 10:03, Nuutti Kotivuori wrote:
> /snip
> > Hmmh, okay. But, since GPRS is really blocked for the duration of the
> > call, doesn't that mean that the local PPP client will not get replies
> > to LCP echo packets? So atleast the local ppp must be configured to
> > never disconnect the call on LCP echo failures. What about the remote
> > side? Surely there must be some time after which the remote ppp will
> > disconnect your client for not answering to anything - or is there?
> /snip
> > -- Naked
> My understanding, and someone please correct me if I am wrong, is that
> the gprs and gsm functions will be multiplexed by code written by
> Heralde. So it should be possible to use gprs and make a call over gsm
> at the same time.
> --Tim

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