Level 1 Security; Level 2 Security; Level 3 Security - ZyXEL Communications omni TA128 User Manual

Level 1 security

Will only perform password checking. With Level 1 security, the
local TA will maintain the connection if the password is matched,
otherwise the line will be disconnected.

Level 2 security

Provides Calling Party Number checking and call-back, the call-
back number is pre-stored in the password table. If the password
has been matched (in a maximum of 3 tries over a 40 second time
period) with its pre-stored password list, the local TA will check
the Calling Party Number (CPN) (or Origination Address for 1TR6)
against the pre-stored number corresponding to the password. If
they are matched, the local TA will choose either to keep the
connection or to disconnect and then call back according to the
setting of bit 6 of S119:
S119.6=0 - Disconnect and then call back.
S119.6=1 - Keep the connection.
If the CPN does not match with what is stored in the table, the local
TA will disconnect the call. If CPN is unavailable in the SETUP
message, the local TA will disconnect the call and then call back
using the pre-stored number corresponding to the dial-in password.

Level 3 security

Once the password is matched the local TA will prompt the remote
user to enter a call back number.
The three levels of security are summarized in the table below:
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