懂了, 謝謝

Let say ATA has DID 1234 with SG

I want to call destination 5678 from the ATA

The flow of traffic then looks like

ATA -> SS (out plan) -> GV -> GV calls destination 5678, then calls back SG 1234 -> SG then calls SS -> SS (in plan) then calls ATA. At this point ATA 1234 and the destination 5678 are connected.