The network access mode of HSS has been changed to 0 (Packet and Circuit).
Versions of MME prior to v2.4.2 did not use this value. Open5GS set
the attach result of Attach Complete message as it is by looking
at the attach type of the Attach Request message.
Now, if the network access mode of HSS is set to 2 (Only Packet),
this value is affected by MME from v2.4.3. Regardless of the attach type
of the Attach Request, the MME will set EPS Only to the attach result
of Attach Complete.
The AMF shall assign a new 5G-GUTI for a particular UE:
a) during a successful initial registration procedure;
b) during a successful registration procedure
for mobility registration update; and
c) after a successful service request procedure invoked as a response
to a paging request from the network and before the release
of the N1 NAS signalling connection as specified in subclause 5.4.4.1.
The AMF should assign a new 5G-GUTI for a particular UE
during a successful registration procedure
for periodic registration update. The AMF may assign a new 5G-GUTI
at any time for a particular UE by performing
the generic UE configuration update procedure.
If both Delete-Session-Request/Response and
UEContextReleaseCommand/UEContextReleaseComplete are failed at the same time,
UE cannot attach to the EPC infinitely.
So, I've add the protection code
if timer expires when MME does not receive Delete-Session-Response.