Communication is the fundamental process that engages both internal staff and external stakeholders throughout all phases of the Business Continuity Management System (BCMS). According to ISO 22301, an organization must establish, implement, and maintain planned communication arrangements. This involves determining what, when, with whom, and how to communicate with all relevant interested parties. This systematic approach ensures that stakeholders are kept informed, their requirements are understood, and they are actively involved in relevant aspects of the BCMS, from initial planning and risk assessment to incident response and continual improvement. This makes communication the core mechanism for comprehensive engagement.

B. Analysis: Analysis (e.g., Business Impact Analysis) is a specific technical activity to identify priorities and requirements; it is not the overarching process for engaging all stakeholders in all BCMS aspects.

C. Coordination: Coordination is a critical function, especially during an incident or exercise, but it is a reactive or operational activity rather than the continuous, all-encompassing process of engagement.

D. Management: Management provides leadership and resources for the BCMS. It is a function of governance that utilizes communication to achieve engagement, but it is not the engagement process itself.

1. ISO 22301:2019, Security and resilience — Business continuity management systems — Requirements.

Clause 7.4 "Communication": This clause explicitly requires the organization to "determine the internal and external communications relevant to the BCMS including: a) on what it will communicate; b) when to communicate; c) with whom to communicate; d) how to communicate." This establishes communication as the formal process for engaging all interested parties.

Clause 4.2 "Understanding the needs and expectations of interested parties": This clause requires identifying stakeholders (staff, suppliers, customers, regulators) and their needs, which are then addressed largely through the communication processes defined in Clause 7.4.

2. Wong, W. C. (2020). A Competency-Based Approach to Business Continuity. Routledge.

Chapter 4, Section: "Communication with Stakeholders": This academic text emphasizes that "Effective communication is vital for engaging stakeholders at all levels... A BCMS requires a communication strategy that addresses the needs of internal employees, external partners, customers, and regulatory bodies throughout the business continuity lifecycle." This supports communication as the key engagement mechanism.

3. Bajgoric, N. (2014). Business continuity management: a systemic framework for implementation. Kybernetes, 43(2), 214-231. https://doi.org/10.1108/K-06-2013-0115

The paper discusses BCM as an integrated system where communication flows are essential for linking different components and stakeholders. It highlights that "continuous communication with all stakeholders is a critical success factor for embedding BCM into the organizational culture" (paraphrased from discussion on systemic integration).