ghost call

A ghost call is an incoming telephone connection that rings through to completion and registers as connected, but carries no audible conversation, signaling, or presence when the recipient picks up. The caller side may be silent, disconnected, or automated; the recipient hears nothing but dead air or background noise. Ghost calls differ from failed connections, which never complete the ring-through phase, or from dropped calls, which disconnect after conversation begins.

In circuit-switched telephone systems, ghost calls occur when signaling pathways and voice paths become misaligned. The switching equipment may properly route a call request and alert the receiving extension, yet the audio channel fails to establish, bridge, or transmit properly. This can arise from crosstalk between adjacent pairs in copper telephone cables, incomplete trunk connections in larger networks, or timing failures in step-by-step or crossbar switch exchanges where pulses and connections fall out of sync.

In modern digital and VoIP systems, ghost calls are usually traceable to protocol failures. A Session Initiation Protocol (SIP) INVITE packet may successfully trigger a phone to ring and accept the call, but the Real-time Transport Protocol (RTP) audio streams never open or flow only in one direction. Network latency, firewall rules that permit signaling but block media, or mismatched codec settings between endpoints can produce this condition. Some VoIP providers have experienced persistent ghost call clusters tied to specific gateway configurations or border element failures.

Ghost calls also emerge from automatic calling equipment and predictive dialers used in outbound contact centers. These systems send calls faster than agents can answer, creating situations where the dialer routes an answered line to an agent position that is occupied or unavailable. The caller hears silence or a brief hold tone before disconnection. Regulatory bodies including the Federal Communications Commission have issued rules against ghost calls generated by predictive dialers that lack adequate agent availability.

Troubleshooting requires distinguishing ghost calls from ordinary connection problems. Test calls using both handset and speakerphone on suspect lines help isolate audio path failures. Protocol analyzers on VoIP systems can show whether RTP packets are present but silent, or absent entirely. In older networks, technicians used tone generators and loop-back tests on individual pairs to identify crosstalk or open circuits in the voice path after successful signaling.