Network Redirection (Net Redir) is a feature that facilitates the efficient routing of calls across a network. One primary reason to enable this feature is that it supports routing to specific numbers, such as seen in option B. This ensures that calls can be appropriately directed to various endpoints. Additionally, enabling Network Call Transfer (indicated in option D) is another significant reason, as it allows for calls to be transferred seamlessly across the network. Finally, activating this feature can decrease trunk usage and costs (option E) because it optimizes the use of available communication channels, reducing the need for additional trunks and lowering related expenses.