A silent call is a phone call where the caller says nothing and the line remains silent after you answer, eventually disconnecting. While the experience can be unsettling, many cases are actually benign, and understanding the causes helps you respond calmly.
Causes fall into four main categories. First, intentional silent calls as harassment or stalking. Second, malfunctions of predictive dialers (auto-dialing systems) used by call centers. These systems dial multiple numbers simultaneously and connect answered calls to operators, but when all operators are busy, the call has nowhere to go and becomes silent. Ministry guidelines require businesses to keep such "abandoned call" rates below 3%. Third, misdirected fax transmissions - when a fax machine dials a voice number, you may hear only a "pee-hyoro-ro" signal tone or complete silence. Fourth, robocalls checking whether a number is active, which simply record whether the call was answered and disconnect immediately.
Silent calls and one-ring calls are often confused but differ in nature. One-ring calls cut off after 1-2 rings to lure a callback to a premium-rate number. Silent calls involve silence after the call is answered, with psychological distress rather than direct financial harm being the primary concern. When repeated during late-night hours, they can cause anxiety disorders and sleep disturbances, so they should not be dismissed as mere nuisance.
For countermeasures, first use Number Display to check the caller, and if the call is anonymous, set your phone not to answer. If the same number repeatedly makes silent calls, add it to your call blocking list. Enable call recording to preserve evidence, which is useful when consulting police. In severe cases, anti-nuisance ordinances or the Anti-Stalking Act may apply, with criminal penalties possible. See The Mystery of Silent Calls for detailed cause analysis and How to Block Nuisance Calls for setup instructions.