Hi Holger,
just to explicitly respond to this sentence in your first message on the subject:
On Sun, Jul 28, 2013 at 10:01:04PM +0200, Holger Hans Peter Freyther wrote:
So this means that for the entire GPRS attach procedure we will use the initial foreign TLLI....
Which I believe is correct. The RAU_COMPLETE / ATTACH_COMPLETE should be the first message in downlink containing the new TLLI from my point of view.