Change in ...osmo-bts[master]: common/rsl.c: fix: properly handle SI3 Rest Octets

fixeria gerrit-no-reply at
Wed Jul 17 12:19:50 UTC 2019

Hello laforge, laforge, Jenkins Builder, 

I'd like you to reexamine a change. Please visit

to look at the new patch set (#2).

Change subject: common/rsl.c: fix: properly handle SI3 Rest Octets

common/rsl.c: fix: properly handle SI3 Rest Octets

It was noticed with old Sony Ericsson phones (like W595 and K510i)
that the service provided by Osmocom network becomes unreliable
from time to time. The RSSI indicator on those phones shows that
the signal is lost, so neither CS nor PS services are working.

As it then turned out, System Information 3 broadcasted on the
Um interface is different than the one received from the BSC.
In particular, the content SI3 Rest Octets IE is different.

Among with the 'GPRS Indicator', which is actually expected to
indicate whether the PCU is connected or now, SI3 Rest Octets
on the Um interface contain both 'Optional Power Offset' and
'Scheduling if and where' IEs, which are not present in the
original messages from the BSC.

Moreover, as soon as the PCU is connected, 'GPRS Indicator' IE
contains different 'GPRS RA Colour' value, and informs the MS
that System Information 13 is sent on extended BCCH, which
is not even supported by OsmoBTS!

The culprit is in rsl_rx_bcch_info(), where we pass a pointer
to osmo_gsm48_rest_octets_si3_decode(). Instead of passing a
pointer to the beginning of SI3 buffer, we actually need to
shift it to the beginning of the SI3 Rest Octets IE.

This change makes my Sony Ericsson phones happy ;)

Change-Id: Ia962cf21903ba674057cf52746996dd3254bc1c6
M src/common/rsl.c
1 file changed, 3 insertions(+), 1 deletion(-)

  git pull ssh:// refs/changes/17/14817/2
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: Ia962cf21903ba674057cf52746996dd3254bc1c6
Gerrit-Change-Number: 14817
Gerrit-PatchSet: 2
Gerrit-Owner: fixeria <axilirator at>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria <axilirator at>
Gerrit-Reviewer: laforge <laforge at>
Gerrit-CC: tnt <tnt at>
Gerrit-MessageType: newpatchset
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