Re: [Openbts-discuss] force mobile station to disconnect from network

[Harald W. <la...@gn...>]

Hi Felix,

On Tue, Jan 25, 2011 at 11:59:13PM +0100, Felix Trojan wrote:
> But there seems to be a kind of bug:
> 
> When a MS camps for the first time everything is fine(make calls,
> send sms etc), but when I restart OpenBTS while the phone is still on, it
> reconnects but no IMSI gets added to the table(I don't save the table).

This is the normal behavior as specified by the GSM specification.  If the
current serving cell disappears and re-appears, you are still in the same
location area.

Location Area Update is only performed either
 * when the MS switches on
 * when the MS switches from a different network to your network
 * when the MS performs cell re-selection and old LAC != new LAC

> Therefore  I need a method to drop the phone as OpenBTS exits, so
> that it does like a fresh connect the next time.

The phone is behaving as per spec.  Your network-side is violating the
spec by loosing state that is required to be volatile.

There is nothing you can do to trigger a location area update of a single
phone.

What you could do is to change the LAC of your cell, but then _all_
phones will try to perform a location area update at the same time, i.e.
potentially extremely high load.

> In short: Is there a way to force a MS to disconnect?

the phone is disconnected, as it has no dedicated channel at the time this
happens.

If you really want ot kick a phone off your network, you would have to know
the IMSI/TMSI of the phone (from its last registration), page it, send an
MM AUTH REQ and respond irrespective of the response with an MM AUTH FAIL.

Regards,
	Harald
-- 
- Harald Welte <la...@gn...>           http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)