Dialogic 6.2 - Manual (Page 317)

November 2009 317
BSMI interprets undecoded Q.931 packets from the network,
removing information not needed by most applications and making it
available via an L3L4m message. If you need specific Q.931
information not delivered with the message but that is documented
as contained in a Q.931 packet, such as call setup messages which
have two IEs (Information Elements) – Lower and Higher level
compatibilities, you can get access to the entire undecoded packet via
an L3L4mRAW_QDATA message (see the BSMI section of the Bfv
API Reference Manual, Volume 5, for details). Raw data for Q.931
packets that are not even processed by BSMI in the first place and
for Q.931 packets containing user-defined ISDN messages is also
notified via this message.