Final answer:
Ignoring customer inquiries is the strategy that will not ensure effective customer service over the telephone. Instead, excellent customer service is based on clear communication, accurate information, and active listening.
Step-by-step explanation:
The strategy that will NOT ensure effective customer service over the telephone is C) Ignoring customer inquiries. Effective customer service is built upon several key pillars: speaking clearly and professionally, providing accurate information, and listening actively. Ignoring customer inquiries undermines the process of establishing trust and addressing the needs of the customer, which is critical in delivering good customer service. Instead, it is important to address every inquiry with attention and respect to maintain a positive customer relationship and to provide a solution or a clear path towards one.