Many companies, if they have communication plans at all, still rely on manual call tree lists. The effectiveness of manual call trees is questionable even under normal conditions, but they become almost futile if you want to communicate with thousands of employees at a time of crisis when many telecom and mobile services are unavailable. The good news is that Internet access can still be available, allowing calls to be made with VoIP, correspond via email and instant messages, and use social networking sites such as Facebook and Twitter. Forrester recommends using multiple modes of communication and, ideally, automating them, as well as leveraging social media to your advantage. (Source: Forrester)