gprs_gmm: Fix bit mask when determining update/attach type
Bit 4 is reserved in 3GPP TS 04.08 so exclude it from the type.
In 3GPP TS 24.008 it indicates if a follow-on request is pending by the
MS, but only in Iu mode. According to the spec it is not required to
react to that request with a follow-on proceed so this field can be
ignored for now.
See 3GPP TS 24.008 Ch. 4.4:
"Unless it has specific permission from the network (follow-on proceed)
the mobile station side should await the release of the RR connection
used for a MM specific procedure before a new MM specific procedure or
MM connection establishment is started."
as well as Ch. 4.4.4.6:
"If the network wishes to prolong the RR connection to allow the mobile
station to initiate MM connection establishment (for example if the
mobile station has indicated in the LOCATION UPDATING REQUEST that it
has a follow-on request pending) the network shall send "follow on
proceed" in the LOCATION UPDATING ACCEPT and start timer T3255."
Change-Id: If1dff960c406060e257dafc54132687ffc42ad8f
1 file changed