in the grid. When setting up each call through the fabric, but before connecting the fabric to the line and/or trunk, the controller could connect a test scan point to the talk wires in order to detect potentials. Current flowing through the scan point would be reported to the maintenance software, resulting in a "False Cross and Ground" (FCG) teleprinter message listing the path. Then the maintenance software would tell the call completion software to try again with a different junctor.

With a clean FCG test, the call completion software