AT&T SYSTEM 25 Manual page 99

Using Remote Access
From a Touch-Tone Phone
1
Dial the Remote Access number.
2
Listen for the brief whistle and dial tone.
3
If a Barrier Code is required, dial the five-digit Barrier Code and listen for
dial tone.
4
Dial the desired feature, station, or outside line access code and
telephone number.
NOTE:
too slowly or your call was restricted by System 25.
From a Dial Pulse (Rotary) Phone
1
Dial the Remote Access number.
2
Listen for the brief whistle and dial tone.
3
Wait for the dial tone to timeout; the attendant (or back-up
person) will place the call.
2-86 Voice Terminal Features
If you hear fast busy tone, you either dialed