AT&T Classic Mail Voice Messaging System User Manual page 44

CLASSIC MAIL System Mailbox User Guide
Off-site message alert works this way:
Set up off-site message alert by entering the
phone or pager numbers at which you want
to be contacted. (You can list up to two
phone numbers to be called in succession or
up to two pager numbers or one of each.)
Turn on the feature when you leave your
office and indicate whether you want to be
alerted to all new messages or only those
marked urgent.
The CLASSIC MAIL system calls you "n"
times at the first number at regular intervals,
where "n" is the number of call attempts you
set. (You set the number of call attempts
between 1 and 9, and the interval between 5
and 999 minutes.)
Next, if you specify a second number, the
CLASSIC MAIL system calls you there the
specified number of attempts.