What type of device should be installed for surveillance?

CCTV, or Closed-Circuit Television, is specifically designed for surveillance purposes. It consists of cameras that transmit video footage to a monitor or a recording device, allowing for the observation and recording of activity in a particular area. This makes CCTV systems highly effective for security monitoring in various settings such as retail stores, offices, and public spaces.

In contrast, LAN (Local Area Network) refers to a network that connects computers within a limited area, typically for data sharing and communication, but it does not provide surveillance capabilities. A router is a networking device that forwards data packets between computer networks, facilitating internet access and data communication rather than surveillance. PABX (Private Automatic Branch Exchange) is a telephone switching system used within an organization, primarily for managing internal phone lines and calls, which also does not relate to surveillance.

Thus, CCTV stands out as the appropriate choice for surveillance needs due to its intended function and design.