E911

Basic 911 connects a caller to a PSAP. E911 adds automatic number identification (a callback number) and automatic location information so dispatchers are not guessing from a spoken address alone. On the legacy PSTN, that location came from a wire-map / ALI database keyed to the line. On VoIP and multi-line telephone systems (MLTS), the phone can move. The location in the database can be wrong unless someone keeps it current.

Dispatchable location

FCC rules implementing Section 506 of RAY BAUM's Act use "dispatchable location": a location delivered to the PSAP with a 911 call that consists of a validated street address plus additional information such as suite, apartment, floor, or room, sufficient for first responders to find the caller. A street address for a 40-story building without a floor is not enough. "Validated" means the address is a real deliverable location, not a free-typed string nobody checked.

Kari's Law

Kari's Law (2018) is named for Kari Hunt. In 2013 her daughter could not reach 911 from a motel phone because the MLTS required a prefix (dial 9) for an outside line. The statute, implemented by the FCC, requires that MLTS in the United States support direct 911 dialing: the user must be able to dial 911 without a prefix or access code. Systems must also notify a central location (front desk, security) when 911 is called, with callback and location information, without delaying the 911 call itself. The notification runs alongside the call; it does not gate it.

• Direct 911: no "dial 9 first" as a requirement to reach the PSAP.
• Notification: someone on-site or at a central point should know a 911 call happened.
• The 911 call itself must not wait on that notification.

RAY BAUM's Act and MLTS

RAY BAUM's Act Section 506 directed the FCC to address dispatchable location for 911, including from MLTS, regardless of technology. In 2019 the FCC adopted rules that apply to persons who manufacture, import, sell, lease, install, manage, or operate MLTS in the United States. Deadlines were staggered: on-premises fixed phones (automated dispatchable location by 6 January 2021) and on-premises non-fixed plus off-premises devices (6 January 2022, with feasibility alternatives such as end-user manual update or specified alternative location information). Those deadlines have passed. Systems installed after 16 February 2020 also fall under Kari's Law's forward-looking requirements.

MLTS, desk phones, and remote devices

MLTS

A multi-line telephone system: hosted PBX, on-prem PBX, or similar that serves multiple extensions. Hotel, hospital, campus, and office VoIP platforms are the usual examples.

On-premises fixed

A phone that stays in a known room. Location should be automatic from the wiremap or admin database.

Off-premises / softphone / WebRTC app

The user must have a way to set or confirm a dispatchable location. A default HQ address is the classic remote-work failure.

Forwarded cell

Answering a business call on a mobile phone does not make that mobile the MLTS 911 endpoint. 911 on the cell uses the wireless E911 path, not the office registered location.

NG911

Next Generation 911 (NG911) replaces analog CAMA trunks with IP (typically SIP) into an Emergency Services IP Network (ESInet), using standards from NENA (i3). It can carry richer location (PIDF-LO civic and geodetic) and, over time, multimedia. NG911 is the PSAP-side architecture. It does not remove the enterprise duty to supply a correct dispatchable location on the 911 call. A SIP 911 INVITE with the wrong location object is still a wrong dispatch.

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