On Tue, Apr 14, 2009 at 01:10:36PM +0200, Andreas.Eversberg wrote:

on the easterhegg 2009 we got everything running. even audio worked! and we catched our first imsi from a public network.

congratulations. It's good to know that others can reproduce our work.

the following things must be changed in the software:

• sending time slot 1 frames requires a queue and a timer, rather than

using "usleep()". sleeping causes loss of audio and signalling informations. (i work on that)

I completely agree. the usleep() was just a quick and dirty hack.

• subslots are in reverse order: slot 2 (0..3) must have mask 00110000

and not 00001100. this causes no audio.

• both time slots (2 and 3) must be configured, or unitialized pointers

cause a crash.

interesting. Why was it working for us here before?

• data link is available since DL_ESTABLISH_IND is received and not

MPH_*.

ok. This is a misunderstanding of mISDN on my part.

• in order to release layer 2 and unload the driver after stopping of

bsc_hack, a special ioctl must be given after opening socket.

the question is: do we want this? At least during development, I don't think so. The BS-11 has the nice property that you can just restart OpenBSC and everything will keep working. The BCCH stays alive, phones in idle mode don't even notice tha OpenBSC was restarted.

This is very different from the nanoBTS, where the BCCH dies as soon as the TCP connection to OpenBSC is down. You need to perform network selection again after restarting OpenBSC.

So if we release layer 2, then we should at least have a commandline option to keep the current behavior.

• some little extras: changing card number and "location area code" by

additional arguments.

@harald | @dieter: other isdn drivers (windows) have obviously reversed bit order on transparent channel. bit 0 is exchanged with bit 7 and so on. to make it work, i did not change the bit order, i just changed the location of the subslot, and it worked.

I am using mISDN with HFC-E1 and BS-11 on a Linux x86 box without changing anything regarding the subslot bit order. I think at least three people have wokring BS-11 + OpenBSC setups. So I'm a bit surprised that you bring up the bit order now. Was it only coincidence when it worked so far? Maybe this needs more investigation.

i would like to provide a patch for the solutions above. i will see, if i can do that this weekend.

great, please one patch per problem, if possible.

• provide a real state machine to the layer 3 with timers. make calls

setup and release cleanly.

• support transcoding of all information elements.
• remove all call/subscriber handling from layer 3 and put it into a

seperat file (layer 4 call control). it will then be possible to initialize libbsc without the built-in call control and database, to use it for other applications like asterisk and linux-call-router.

• add application interface to traffic channels for transcoding and

switching.

I agree with those goals, so if there are any issues from my side, they would likely only relate the implementation of it, not the goal/target.

the estimated time for this will be about 2-3 months. the result will be a complete BSC+MSC with routing and PBX features and asterisk interface. i will provide a patch en-block, because i work on all parts at the same time.

ok. It would be great if you could keep us in the loop, e.g. use a public set of patches, or a svn branch in our repository, or something similar. If we can keep up-to-date with what you're doing, we can probably give better feedback than if we have to wait for three months and then get thousands of lines of patches that need to be reviewed all at once.

Thanks again for all your help, it is really appreciated.