AT&T MERLIN LEGEND Release 3.0 System Programming And Maintenance Manual page 124

Glossary
W
WATS
wink-start tie trunk
GL-34 System Programming and Maintenance (SPM)
(Wide Area Telecommunications Service)
Service that allows calls to certain areas for a
flat-rate charge based on expected usage.
Tie trunk on which the originating end transmits
an off-hook signal and waits for the remote end
to send back a signal (a wink) that it is ready
for transmission.