8 Jul
2014
8 Jul
'14
2:31 p.m.
Hello again,
Holger Hans Peter Freyther wrote:
it is not a question of BTS but the BSC. The role of
the BSC is to manage
the
channels. Inside src/libbsc/gsm_04_08_utils.c you will
see a table that
determines how the BSC/NITB will respond to "channel request" inside the
RACH request by the phone.
E.g. if you change get_ctype_by_chreq to always return LCHAN_SDCCH you
should be close to the behavior you have described.
First off all: Thank you for your fast response.
I was hoping that it would be enough to change the settings in the
open-bsc.cfg and I wouldn't have to temper the source code, as I said, I'm
new to all the GSM stuff and Linux.
I had a quick look at the code and just tried to comment out everything in
"get_ctype_by_chreq" and always return LCHAN_SDCCH as you suggested.
While testing this setup I saw, that The "Immediate assignment" now sends
the calling MS to TS 1 (which is configured as SDCCH/8) subslot 0 and
starts encryption and sends SI5 and SI6 messages on this timeslot/subslot.
Also the called MS gets "Immediate assignment" and is sent to TS 1 subslot
1, encryption starts and so on.
Now the called MS sends "Call Confirmed", but shortly after this the
channels are released. (The called MS wasn't ringing at all)
Am I right, that this is because both MS are yet sticking on the SDCCH and
are not going to a Transport channel? (would make sense, because I always
return SDCCH when the BSC wants to change channel)
I think I have to change the Table " ctype_by_chreq" or to find a way to
insert another "Immediate Assignmend" between "encryption" and
"call
confirmed"
So I think I'll have to study the source code for a while,
Again thanks for the hint where to start.
[Norbert Englberger]