[Commotion-dev] FYI: Serval & OpenBTS integration

[Alexander Chemeris]

Hi Dan,

I apologize for slow response. I haven't paid attention to my e-mails
this week due to high workload.

On Wed, Nov 14, 2012 at 8:34 PM, Dan Staples
<danstaples at opentechinstitute.org> wrote:
> Thanks Alexander, we'll try all those suggestions. Do you know if
> Asterisk needs to be running in order for OpenBTS to write to the
> Subscriber Registry db, or does OpenBTS write directly to the db?

Asterisk doesn't write to Subscriber Registry db. It's sipauthserve
and OpenBTS who write to it. IIRC, OpenBTS only writes non-essential
things like IMEI and RRLP coordinates to it, while sipauthserve writes
the actual phone location (aka IP:port) to it. This have to be checked
vs the code to be sure.

What issue do you have with this?

> Also, you mentioned at the Hackday that some phones have compatibility
> problems with OpenBTS...what exactly about those phones in incompatible?
> Is it certain brands or chipsets?

Different chipsets has different GSM stacks and thus their behavior is
different. Also there are chipsets with buggy GSM stacks (esp. Chinese
ones), which doesn't make life easier. To add some salt, OpenBTS
implementation of GSM is not complete - GSM uses state machines, while
OpenBTS assumes it's a linear sequence of messages. And we already
know some places where this breaks execution and OpenBTS just hangs a
call instead of processing it. I'd love to fix this, but it requires
quite some time and effort.

--
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru