Справочное Руководство для Netopia 430 s

Calling Number Authentication (CNA), is an application of caller ID. 
It is a method of verifying that an incoming call is originating from an 
expected site. Using CNA, you can increase the security of your 
network by requiring that callers not only possess the correct PAP or 
CHAP information, but also that they are calling from a par ticular 
physical location. CNA should be available where caller ID ser vices 
are available, but you will need to consult with your ISDN ser vice 
provider to find out if your ISDN line is provisioned for caller ID.

CNA works by checking the calling number that the Netopia ISDN 
Router receives during the initial setup phase of an incoming call 
against the stored Calling Number defined in each connection 
profile. When a match occurs, the incoming call is handled by the 
connection profile containing the matched number.

Using CNA can also provide cost saving because calls are not billed 
during the CNA phase. With CNA, a caller can set up a connection to 
the Netopia ISDN Router without incurring any charges by accessing 
a dial-back connection profile. If the callers rates are higher than 
those charged to the Netopia ISDN Routers return call, then using 
CNA has saved the difference.