ZyXEL Communications Prestige100 user manual

However, CLID may not be available due to your switch configuration.

Besides authentication, another application of CLID is to combine it with call back. For instance, your company pays for the connection charges for telecommuting employees, and you are using the Prestige as the dial in server. You can turn on both the CLID authentication and call back options for the dial-in users. By doing so, all usage are charged to the company instead of the employees, and your accounting department can avoid the hassles of accountability and reimbursement.

68 Dial-In Configuration