External interface for USSD
we already have SMPP for SMS, but don't have similar functionality for USSD, i.e. a way in which external applications can exchange USSD with MSs.
There are some provisions for USSD in SMPP, but I think they don't really appreciate the session-oriented nature of USSD.
In either case, I'm not aware of any standard to hand USSD to external applications. Of course there's MAP, but nobody wants to implement that in an external application...
- Processing / forwarding of the Cause IE in GSM 04.80 RELEASE COMPLETE message
- Processing of SS Version IE in MO GSM 04.80 REGISTER message
GSUP: implement TCAP-like session management
Unlike TCAP/MAP, GSUP is just a transport layer without the
dialogue/context. This prevents us from having session based
communication, required e.g. for USSD. But we can emulate
TCAP dialogue by adding additional IEs, which would allow
to relate each message to a particular session.
This change introduces the following IEs:
which optionally can be used to indicate that the message is
related to a session with given ID, and to manage session
state, i.e. initiate, continue, and finish.
GSUP: introduce new messages for SS/USSD payloads
In order to be able to transfer SS/USSD messages via GSUP,
this change introduces the following new message types:
and the following new IE:
which represents an ASN.1 encoded MAP payload coming to/from
the mobile station 'as is', without any transcoding.
#6 Updated by fixeria about 3 years ago
If anyone has and/or can record LAPDm traces of USSD sessions with a commercial
network or even MAP traces, I would be more than happy.
There is a sample capture:
but one is too trivial...
#7 Updated by fixeria about 3 years ago
Oh, WOW! I've just found a MAP trace with lots of USSD sessions.
This is exactly from where I took the pictures above.
#9 Updated by fixeria about 3 years ago
- File ussd_ms_init.png ussd_ms_init.png added
- File ussd_net_init.png ussd_net_init.png added
- File ussd.xml ussd.xml added
I've visualized some possible USSD-session examples...
The images are created using https://draw.io, and can be opened
and edited (source XML attached) there.
#10 Updated by fixeria almost 3 years ago
- Status changed from In Progress to Feedback
- % Done changed from 50 to 90
The new changes which implement support of both MS-initiated and network-initiated
SS/USSD transactions have been send to review:
The only missing part at the moment is notification about errors,
e.g. when Paging of a subscriber is failed, or when a message decoding is failed.