GSM specs doubt

Harald Welte laforge at
Mon May 9 13:16:33 UTC 2011

On Mon, May 09, 2011 at 11:40:07AM +0000, Gerard wrote:
> Hi list,
> while studing burst_ind (I know that burst_ind must be used in a own controlled
> network) i see that one SDCCH for a specific operator has been shared by more
> than one MS (different TMSIs), some MS use for SMS other use for calls. Is that
> an interpratation error (due the fact of using burst_ind in real networks) or
> that could be possible? i didn't find explanations on sepcs.

It's called SDCCH/8 or SDCCH/4 since one on-air timeslot (physical
channel) is used to generate 8 (or 4, respectively) SDCCH logical

in GSM, everything is TDMA.  Take your time to really understand the
TDMA hierarchy.

- Harald Welte <laforge at> 
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

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