AT&T MERLIN LEGEND Data Manual page 36

Data Communications Hardware
Features
2-6
Modems
Analog data stations (those not in a modem pool) in the system offer the
following features, depending on your modem:
dialing of asynchronous data calls from the keyboard when connected to a
basic telephone station jack on a 012 or 008 OPT module or when connected
to an MLX telephone using an MFM
autobaud (also called data metering or speed matching) for adjusting the
speed of transmission to match the speed of the data terminal being called
automatic or manual answering of incoming data calls
self-test and maintenance procedures
ability to set data options for the call on the keyboard and change-the
options without dropping the call