Which equipment connects multiple internal lines to external lines within a business?

Which equipment connects multiple internal lines to external lines within a business?

• A. Private branch exchange (PBX)
• B. Public switchboard
• C. Central office
• D. Key system

Answer: (A)

A private branch exchange is the equipment that lets many internal extensions share a smaller pool of outside lines. It sits inside the business and routes calls between internal phones and to the external telephone network, so any extension can reach others and access outside lines without each extension needing its own dedicated line. This pooling and routing capability is what makes a PBX the right choice for connecting multiple internal lines to external lines. In contrast, a central office is the carrier’s external switch, a public switchboard is a traditional operator-connected system, and a key system is an older, less flexible setup where extensions often have fixed lines.

A private branch exchange is the equipment that lets many internal extensions share a smaller pool of outside lines. It sits inside the business and routes calls between internal phones and to the external telephone network, so any extension can reach others and access outside lines without each extension needing its own dedicated line. This pooling and routing capability is what makes a PBX the right choice for connecting multiple internal lines to external lines.

In contrast, a central office is the carrier’s external switch, a public switchboard is a traditional operator-connected system, and a key system is an older, less flexible setup where extensions often have fixed lines.