Cisco Unity Connection restriction tables are security mechanisms designed to control outgoing calls from the system to the PSTN or other external destinations. They apply to features like message notifications and call transfers to user-defined numbers, such as an alternate contact number. However, a user's primary "extension number" is an internal identifier within the system and is not a destination for an outbound call that would be subject to a restriction table. Therefore, when an administrator changes a user's extension number in the administrative interface, this action is not validated against any restriction table.

A. This is incorrect. Restriction tables are for controlling external dialing patterns, not for validating internal user extension numbers.
C. This is incorrect. Standard users do not have the ability to change their own primary extension number via the Telephone User Interface (TUI).
D. This is incorrect. Standard users cannot change their own primary extension number via the Cisco Personal Communications Assistant (PCA) web page.

1. Cisco Unity Connection System Administration Guide

Release 12.x

"Users" Chapter

Section: "User Attributes": This guide defines the "Extension" field as the primary number at which a user receives calls. This establishes it as an internal directory number. (Reference: Page 2 of the "Setting Up Features and Functionality That Are Controlled by User Account Settings" chapter).

2. Security Guide for Cisco Unity Connection Release 12.x

"Understanding Security" Chapter

Section: "Controlling Access to Phone Numbers for Calling Out of Unity Connection": This section explicitly lists the call types that are subject to restriction tables. These include "transferring callers to a user's alternate contact number" and "delivering a fax message to a fax machine." The list does not include the configuration of internal user extensions

confirming that restriction tables do not apply to them.

3. Cisco Unity Connection User Guide for the Cisco Unity Connection Phone Interface (TUI) Release 12.x

"Changing Your Settings" Chapter: This guide details the settings a user can change via the TUI. It includes options for changing passwords

recordings

and notification devices

but not the user's primary extension. This supports the reasoning that option C describes an impossible action for a standard user.