Which device provides protocol translation between H.320 (ISDN) and H.323 (IP) networking environments?

• A. GIF
• B. G.711
• C. Gateway
• D. H.239

Answer: (C)

Interoperability between H.320 (ISDN) and H.323 (IP) requires a device that can bridge two different network protocols, handling signaling and media translations as traffic moves between ISDN and IP. A gateway is exactly this kind of device; it terminates one side’s protocols (like H.320/ISDN) and re-encodes or maps them into the other side’s protocols (H.323/IP), negotiating capabilities and maintaining call control and media streams. It may also perform codec transcoding if needed to accommodate endpoint capabilities. GIF is an image format with no role in networking protocols. G.711 is a codec used for audio, not a translating device. H.239 is a protocol for enabling content sharing within an H.323 call and does not bridge between ISDN and IP networks. Therefore, the translator device enabling cross-protocol communication is a gateway.