bsc/ussd: Send faked CM Service Accept before sending USSD

The MS do not show the USSD messages yet. This patch modifies the
implementation to insert a CM Service Accept to finish the
establishment of the MM connection according to 3GPP TS 04.10/3.2.1
before the USSD notification is sent.

This fix has been tested with a Blackberry phone that has shown
an ussd_grace_txt after rf_locked has been set to '1'. Without this
patch, that message wasn't shown. The phone has sent a CC Setup
and other messages before processing the channel release message sent
by the BSC, but these messages have not been forwarded to the MSC (as
expected).

Ticket: OW#957
Sponsored-by: On-Waves ehf
1 file changed
tree: f52ca2bfe14cde8737d0802ce2bceeecc1b74971
  1. debian/
  2. hlrsync/
  3. linux-kernel/
  4. openbsc/
  5. wireshark/
  6. README