Answer:
The '-S' suffix designates the inclusion of local picture memory, enabling the DS-KH2220-S to capture, store, and play back visitor snapshots. The base DS-KH2220 provides real-time video and intercom audio without internal image capture storage.
Within Hikvision's 4-wire analog intercom portfolio, the model code suffix '-S' denotes local storage functionality. While the standard DS-KH2220 provides hands-free two-way audio, live video monitoring, and remote door release, it lacks memory for recording visitor activity.
The DS-KH2220-S incorporates dedicated image storage hardware, firmware support for captured picture storage and playback, and a physical Image Key on the chassis control strip. Both units share the same 7-inch 800 × 480 TFT LCD, 12 VDC electrical profile, 4-wire terminal interface, and support for up to 3 cascaded indoor stations.
