A user forwards a corporate number to an international number. What are two methods to prevent this forwarded call? (Choose two.)

The most direct method to control call forwarding is by assigning a specific Calling Search Space (CSS) to the "Forward All" setting on a user's directory number. This "Forward All CSS" can be configured to lack access to the partition containing international route patterns, thereby blocking the forwarded call. Alternatively, configuring a Forced Authorization Code (FAC) on the international route pattern also prevents the call. The automated call forwarding mechanism cannot provide the user-specific code required to complete the call, causing the attempt to fail. Both are effective methods for preventing toll fraud via call forwarding.

B. The SIP trunk's CSS governs calls originating from the trunk, not calls routed to the trunk from an internal phone's forwarding settings.
D. Call Classification is primarily used for call detail recording (CDR) and specialized routing logic (like TEHO), not for blocking calls.
E. "Route Next Hop By Calling Party Number" is a feature that alters gateway selection based on the caller's number, not a call-blocking mechanism.

1. Cisco Unified Communications Manager Administration Guide, Release 14SU3, "Directory Number Configuration" chapter, "Configure Directory Numbers" section, "Line Settings in a Phone" table. This document details the "Forward All" settings, including the dedicated "Calling Search Space" field used to apply a specific class of service to forwarded calls.

2. Cisco Unified Communications Manager Features and Services Guide, Release 14SU3, "Forced Authorization Codes" chapter, "Forced Authorization Codes" section. This guide explains, "When a user makes a call through a route pattern that is configured for FAC, a tone prompts the user to enter an authorization code." This requirement for manual entry effectively blocks automated processes like call forwarding.

3. Cisco Collaboration System 12.x Solution Reference Network Designs (SRND), "Unified CM Call Processing" chapter, "Class of Service" section. This guide describes the best practice of using partitions and CSS to control access to features and destinations. It explicitly mentions applying a more restrictive CSS for call forwarding to prevent toll fraud, which aligns with option C.