What's the meaning of a covert call？

As an AI language model, I don't have personal views or beliefs, but I can provide you with the definition of a covert call. A covert call refers to a phone call made secretly or discreetly, often with the intention of keeping it hidden from others. This type of call may be made for various reasons, such as discussing confidential or sensitive information, avoiding detection or surveillance, or communicating with someone who is not supposed to be contacted.