A common feature sold in the NZ market and labeled as 'Clear Forward Reversal' indicated to a PABX system the exact time a call has disconnected, usually for accurate billing and/or where the disconnect tone wasn't enough by itself to indicate a call has been dropped. Setting this on a SmartWare FXS port imitates this service for connection to legacy PABX systems.
Example:
port fxs 0 1
end-of-call-signaling loop-break 600
use profile fxs nz
encapsulation cc-fxs
bind interface IF_FXS_1 switch
no shutdown