Wireshark-dev: [Wireshark-dev] Decoding TCAP/MAP when SCCP CgPA, CdPA have no SSN

From: Cristian Constantin <const.crist@xxxxxxxxxxxxxx>
Date: Mon, 29 Dec 2025 12:24:15 +0100
Hi,

It looks like Wireshark has some problems decoding TCAP/MAP payloads
of SCCP UDTs when there is no SSN in the CgPA, CdPA...

What I have tried...

1. "Decode as..."; however, for SCCP payloads this works only on some
specific SSN. And SSN is not present in the CgPA, CdPA...
2. Preferences/Protocols/SCCP/User Table; again SSN is explicitly
required. Is it possible to configure it _without_ an explicit SSN
(based on the PC, NI aso?)
3. Preferences/Protocols/SCCP/Default Payload: TCAP. This one works
for _most_ of the TCAP/MAP payloads. However there are SCCP UDTs for
which Wireshark is decoding only the TCAP information (i.e. Continue,
End, the tids aso) but it cannot decode the MAP component. Any idea
why?

Version information:
Version 4.6.2. on Linux/Ubuntu 22.04

Thanks a lot,
Cristian

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