The FOUR most common types of listening devices found during these professional inspections by JRS INVESTIGATIONS in VAIL, CO: 1. RF (Radio Frequency) Transmitters: These miniature, battery-powered or hard-wired bugs capture conversations and transmit them via radio waves to a receiver nearby 2. Cellular/GSM Bugs: These devices utilize local mobile networks (using a SIM card) to stream live audio to … Continue reading 4 Listening Devices Found TSCM Bug Sweeps VAIL Colorado