Telebit T3000 Reference Manual page 105

When password security is enabled (S46 is not 0),
you must enter the -U (system callback security)
password before the modem accepts the change .
... u
Update Security Password
See also: S46
The -U command allows you to change the system
callback security password, which you must give in
order to change the value of the S46 register. This
password is also required in order to change an entry
in the telephone number directory if callback security
is enabled (S46 is not equal to zero).
When you enter the -U command, the modem asks
for the old password (PEP is the factory default,
entered in upper case), the new password, (entered in
any combination of upper and lower case), and a
confirmation of the new password.
After changing the password, the modem asks you to
enter a new prompt string (up to 20 characters) to
display at the caller's terminal. The default value of
this prompt string is "Enter Password:". Use a
carriage return to retain this prompt string.
Note:
The modem ignores any commands on the command
line following the-U command.
-V(n) View Nonvolatile Configurations
Range: O or 1
This command displays the nonvolatile modem
configurations. The display header shows which
configuration is displayed (A or B).
-v
Same as -VO.
5-30 AT Command Descriptions