Suitable for use in cities, schools, hospitals and residential compounds Two channels CMS can been exponded up to 16 channels. Main Features 1. Caller ID display and alarm; caller tracing; 2. Automatic CONTACT ID,4+2 EXPRESS,4/2,4 /1 and 3/1 policing call format identification; 3. Convenient installation and setup 4. Lightning-proof 5. Police call buzz reminding 6. Real-time telephone line status ...