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]