Trunk between 2 PABX


I’ll explain my problem, I currently have a trunk between a PABX1 (Freepbx) and a PABX2 (3CX).
Currently I can receive and manage the SDAs that I see again through the Trunk on my 3CX without any problems but it’s impossible to make outgoing calls knowing that I have another sip trunk to my operator on PABX1, which allows me to recover the SDAs that I put in the trunk between PABX1 and PABX2.
Do you have any idea ?