Postilion FEP and T24 message specification

Hello all, I am new to this site and newbie to working with T24 core banking server. I have worked with C24 previously when deploying our Business Transaction Monitoring tool called Inetco Insight for financial institutions. However, I have a challenge with T24. Can someone help me with the message specification between a Postilion FEP and T24? The link I am monitoring is: ATM<--->FEP<--->T24. I was told by the Postilion support staff that the message format between FEP<--->T24 is ISO8583, However on capturing a wireshark trace of some transactions from their test ATM, I see that the messages between FEP and T24 has other messages alongside the standard ISO8583. Hence, my tool which has the standard ISO8583 fields specified is still representing the transactions wrongly or is truncating some fields.

Kindly assist.

This question could have gained more response on ISO8583 forum. Iso message have fields which can be customize for particular situation like fields 127, i can put whole output of STMT on it. So you need to understand the bitmap which has been used for that message for you to be able to decode the message successfully.

Are you the one who is also handling the Postilion. Please agree on correct bitmap which you can process with your postilion team. This issue you can handle it quite easy from your end.