AT&T Merlin II Feature Module 2 Data Communications Manual page 55

REQUIREMENTS FOR
OUTGOING MODEM
POOLS
REQUIREMENTS FOR
INCOMING MODEM POOLS
Modem Pools
3-18
In addition to meeting the systemwide requirements, a modem used for
outgoing calls must have the following characteristics:
Touch-Tone dialer that can pause and can dial digits 0 through 9, #,
and *.
Detection of dial tone
Ability to take terminal dialing instructions
EIA lead DSR and RLS on before a call is placed (follows DTR)
In addition to meeting the systemwide requirements, a modem used for
incoming calls must have the following characteristics:
Auto-answer feature
Compatible parity and character length with MTDM