Transfer variables to another PBX


I’ve create a extension to capture credit card informations. I used the variable ${BLINDTRANSFER} to get what I needed and using CUT’s I was able to get it working.
My problem now is the I have to use the credit card extension in another PBX, wich is integrated via via SIP trunk, but I don’t receive the information of the variable.

Using DumpChan I see: CallerIDNum and DNIDDigits, but I don’t have the extension who transfered the call.

Any siggestion of how could I passe this information to the destination PBX?