Nokia 12 GSM MODULE REMOTE I/O Control Manual page 20

Figure 5. Security settings
Authentication
A user-specified password can further secure the communication between a
mobile handset and the Nokia 12 GSM Module. The password must be entered
when a control message is sent to the Nokia 12 GSM Module. When this
feature has been set on, but the password is missing or incorrect, the message
received is discarded. Activate or change the password with Configurator or
with a control message (see Chapter 9.3.1).
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