I believe the only way is to use UUI. I use it this way (UUI).
If you don't know how, here's a brief explanation.
1 - In the trunk, go to the "Protocol" section;
2 - enable the option "UUI Passthrough"
3 - select the Encoding Format (HEX or ASCII) - It needs to be the same encoding as the SBC.
4 - in the Architect, create a new variable = flow.UUI = Call.UUIData (flow.UUI will give you the complete data.)
5 - Create a another variable flow.SplitUUI = Split(Flow.UUI,"|") (In my example I used " | " you need to check how it will be sent from GVP, it could be " , " or " ; "...etc)
6 - Create a another variable flow.qtdUUI = Count(Flow.SplitUUI) - (This will tell you how many indexes you have in your UUI.)
7 - Finally, you'll need to work with indexes, because it will return results like this:
flow.SplitUUI[0]
flow.SplitUUI[1]
flow.SplitUUI[2]
flow.SplitUUI[3]
.
.
.
flow.SplitUUI[10]....etc
------------------------------
Kaio Oliveira
Interaxa
------------------------------