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Chapter 5 – Callback Security
14 Multi-Tech Systems, Inc. MT9234ZBA-Series User Guide (S000387D)
Chapter 5 – Callback Security
This chapter describes how to use callback security with your modem. Callback security protects your network from
unauthorized access and helps control long-distance costs. When callback security is enabled, all callers are requested to
enter a password. If a valid password is received, the modem hangs up and returns the call by dialing a phone number that is
stored with the password. The person being called back must then enter the password a second time to establish a
connection.
Up to 30 callback passwords and dialing strings can be stored in the modem. Each dialing string can be up to 34 or 35
characters long and can contain commands as well as phone numbers. For mobile callers, the dialing string can be
programmed to allow the caller to bypass the stored callback number by entering a temporary callback number, to enter an
extension at the callback number, or to make a direct connection without callback.
For local security, the passwords and dialing strings that are stored in the modem are protected from tampering by a setup
password, which you should change when you set up the modem. You can further protect the modem against tampering by
disabling its ability to respond to most AT commands. To check for attempted break-ins, you can request the modem to display
the number of failed password attempts.
Your modem was shipped with a default setup password (MTSMODEM). The same password is used for both callback
security and remote configuration (Chapter 4). Because anyone who has access to this guide has access to the default
password, you should change the password during your initial setup.
Changing the Setup Password
1. Open a data communications program such as HyperTerminal.
2. In the terminal window, type AT#SMTSMODEM (or AT#Sxxxxxxxx if you have replaced the MTSMODEM password
with xxxxxxxx). Press E
NTER. The modem responds with OK if the setup password is correct and ERROR if it is
wrong.
3. To change the password, type AT#S=xxxxxxxx, where xxxxxxxx stands for the password, and then press E
NTER.
The password can include any keyboard character, and can be up to eight characters long. The modem responds
with OK.
4. The new password is saved automatically. You can now either enter more AT commands or exit the data
communications program. The next time you wish to set up the modem, you must use the new password.
CAUTION: Passwords are case-sensitive. The next time you enter the password, it must be in the same case as you
set it up.
Turning Callback Security On and Off
Callback security must be turned on to enter many callback security commands.
1. Open a data communications program such as HyperTerminal.
2. In the terminal window, type AT#Sxxxxxxxx, where xxxxxxxx is your password. Press E
NTER. The modem responds
with OK if the setup password is correct and ERROR if it is wrong.
3. Type one of the following commands:
• To turn off callback security: Type AT#CBS0 and press E
NTER. Callers no longer need a password to connect
to the modem, the modem is unable to call them back, and the stored dialing command locations 0–3 become
available.
• To turn on both local and remote callback security: Type AT#CBS1. Press E
NTER. With local security turned
on, you must enter the setup password before you can enter any AT command except the AT, ATIn, and
AT#Sxxxxxxxx commands. For a description of remote callback security, see the following paragraph.
• To turn on remote callback security only: Type AT#CBS2 and press ENTER. With remote callback security
turned on, each caller is asked to enter a password, is called back, and then is asked to enter the password
again before a connection can be made. Also, dialing command locations 0–3 for use with the DS=y dialing
command are replaced by callback dialing command locations 0–29.
• To temporarily disable callback security if the modem is set to #CBS1 or #CBS2 (for instance, to call
another modem): Type AT#CBS3 and press ENTER. The modem returns to its original setting when you issue
the hangup command (+++ATH) or the modem is reset. Note that if a remote modem breaks the connection,
callback security remains disabled.