Which statement best describes a gateway's role in VoIP?

• A. A gateway provides PSTN interfacing and routing.
• B. A gateway only handles signaling, not media.
• C. A gateway is used to manage video conferences only.
• D. A gateway translates DNS to phone numbers.

Answer: (A)

A gateway in VoIP serves as the bridge between the IP network and the traditional PSTN, providing the necessary interface and routing for calls that cross the boundary. It handles the signaling required to set up and tear down calls between VoIP and PSTN networks and also performs media translation and signaling conversions as needed (for example, between SIP/H.323 on IP and PSTN signaling on the phone network). This is why describing the gateway as offering PSTN interfacing and routing captures its essential role. The other options miss this bridge function or misstate the gateway’s scope, such as implying it only handles signaling, limiting it to video, or dealing with DNS-to-number mapping.