AT&T MERLIN LEGEND Installation & Maintenance Manual page 542

Adapters, Accessories, and Applications
Note: A PFT telephone cannot be used on this port when the
port is connected for a power failure alarm.
Power Failure DID Busy-Out
The PFT port on a GS or LS module can be programmed to
automatically short the busy-out wire pair associated with a
group of DID trunks. Usually an LS line/trunk is used as the busy-
out pair. When a power failure occurs, shorting this busy-out pair
signals the CO that the DID trunks are out of service (see
Figure 71).
Note: To remove the GS or LS module containing the PFT port
for the DID busy-out, you must first short the busy-out pair and
then disconnect the modular cord from the PFT jack. Otherwise,
a false busy-out will occur. Remove the short after the system is
powered up.
Accessories 6-7