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GSM DTAP malformed packet

Hello everyone.

I've got a packet that is technical a call setup from a PRI plugged into a Cisco AS5400. This message is passed via IUA to a server.

Wireshark sees this as "Stream Control Transmission Protocol" > ISDN Q.921-User Adaptation Layer > Radio Signalling Link (RSL) > GSM A-I/F DTAP.

Wireshark complains that this is a malformed GSM DTAP message. And doesn't seem to display any of the raw ISDN message as it comes off the PRI (I'm looking for stuff like called number, source number..etc). I know it's in this particular packet, Because it can be seen in the lower raw section.

I'm not really sure what the message should be. But I don't think it's RSL. Disabling RSL and GSM DTAP just leave the data undecoded.


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