SIP is the safe choice for new deployments — it integrates with standard PBXs, SIP-compatible VMS, and modern unified-communications platforms. Proprietary systems (some legacy Aiphone, Comelit, Axis) tie you to specific head-ends. SIP also future-proofs the investment as PBX choices evolve. Choose proprietary only if you've already committed to a specific platform with strong feature differentiation.

Yes — most modern IP intercoms expose Wiegand or OSDP outputs to access control panels, or REST APIs for direct integration. Video intercoms (2N, Aiphone IX, Axis I8016) often integrate natively with access control platforms. Confirm specific integrations against the controller and head-end you've chosen — generic ONVIF support isn't sufficient for access-control event handoff.

Zone count follows the building floor plan and operational needs. Typical commercial buildings run 4-8 zones — one per major area or floor. Distribution warehouses and schools commonly run 16-32 zones to support targeted communication. Over-zoning adds amp cost and management complexity; under-zoning forces blanket announcements that aren't useful operationally. Map zones to actual decisions before building the system.

Outdoor paging requires higher wattage per area than indoor — wind, distance, and ambient noise consume sound pressure. Plan for 15-30W per speaker on a 70V line at 50-100 foot spacing for general announcements. For emergency notification with intelligibility requirements (UL 2572), use horn-type speakers and confirm the speaker layout meets local code's sound-level-at-listening-position requirements.

Most modern video intercoms (Aiphone IX, 2N IP Style, Axis I8016) include integrated white-light or IR illumination for low-light operation. Confirm the minimum illumination figure and the IR range. For entrances facing direct sun during day and full darkness at night, look for HDR-capable intercoms; cheap units wash out in direct sunlight and lose detail in shadows where faces actually are.