AT&T SYSTEM 25 Manual page 177

Making a Data Call with a Data Terminal
When a data call is made from a data terminal, voice terminal dialing is replaced by
keyboard dialing and call progress tones are replaced by call progress messages. A
message prompts the user to enter the called number from the keyboard. When the
message or
RINGING
is being called.
Dialed Characters
In addition to digits and the " #" and "*" characters on the touch-tone pad, the dialed
number may contain the following special characters:
The parentheses and dash characters ( ( ) and - ) and the SPACEBAR are
used to improve legibility. (The system ignores these characters. )
A percent sign ( % ) or comma ( , ) produces a 15-second pause in dialing.
Multiple pause characters produce longer pauses.
The dollar sign ( $ ) is called the "mark" character, and indicates that the
remaining digits are for end-to-end signaling.
UNDERSCORE or BACKSPACE characters are used to correct previously
typed characters on the same line.
The "at" sign ( @ ) sign is used to delete an entire line and start over with
a new dial prompt.
Each line of dialing information may contain up to 27 characters. All dialing information,
including pauses and ignored characters, must be typed on a single line following the dial
prompt, ending with a
End-to-End Signaling
When a data connection is made to an off-premises destination, it is sometimes necessary to
send additional tones to the remote endpoint after the connection is established. When a
"mark" character ( $ ) is included in the
to be sent to the far end using Touch-Tone signaling. Pause characters ( , or
usually should, follow a mark character.
DIALING . . . COMPLETED
.
[ R E T U R N ]
DIAL:
appears, this indicates the dialed number
line, it indicates that the remaining digits are
Making a Data Call with a Data Terminal
DIAL:
) may, and
%
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