CompTIA Network+ N10-006 Q34

Which of the following network elements enables unified communication devices to connect to and traverse traffic onto the PSTN?

A. Access switch
B. UC gateway
C. UC server
D. Edge router

Correct Answer: B
Section: Network architecture

Explanation:
People use many methods of communication nowadays such as voice, email, video and instant messaging. People also use many different devices to communicate such as smart phones, PDAs, computers etc. Unified Communications (UC) enables people using different modes of communication, different media, and different devices to communicate with anyone, anywhere, at any time.
Many communication methods use digital signals. To send a digital signal over the analog PSTN, you need a gateway (in this case a UC Gateway) to convert the digital signals into an analog format that can be sent over the PSTN.