What is Next Generation 911 (NG911), and how is it different from E911?

Enhanced 911 sends two things along with the voice call. One is the caller's number, known as automatic number identification, or ANI. The other is the caller's location. Federal rules define automatic location information, or ALI, as information "that permits emergency service providers to identify the geographic location of the calling party."

The legacy network delivers both through a chain of lookups, and the FCC's July 2026 order on 911 reliability walks through it. Your provider hands the call to the legacy 911 network, where a switch called a selective router collects it. The router picks the answering center from a routing table. That table is built from the Master Street Address Guide, a database of valid addresses in each center's service area, and from an ANI/ALI database that pairs phone numbers with those addresses. The call then travels to the central office that serves the answering center, "typically along dedicated trunk lines." The center, called a public safety answering point or PSAP, queries the ANI/ALI databases to confirm the location and the callback number.

So in the legacy E911 network, the answering center gets your location from a stored record, and your phone number is the key that retrieves it. The rules for internet phone service were written around that network. Under 47 CFR 9.11, an interconnected VoIP provider must supply E911 as a condition of service. It has to transmit every 911 call with the ANI and the caller's location, and the PSAP has to be able to get that location through the ALI database. That is why a VoIP provider has to obtain a location for the caller. How it does that depends on the service, and we cover the usual step in how to register a VoIP phone for 911.

NG911 replaces the selective routers, trunks and lookup databases with an IP network. The federal definition calls NG911 an "Internet Protocol-based system" that ensures interoperability, is secure, uses commonly accepted standards and lets emergency communications centers "receive, process, and analyze all types of 911 requests for emergency assistance."

The network is called an Emergency Services IP Network, or ESInet, and a 911 authority or its vendors run it. NENA, the association that writes 911 standards, describes ESInets as "engineered, managed networks" built on packet-switched technology that can carry voice along with large amounts of data.

Inside the ESInet, a group of functions called NG911 Core Services does the work of the selective router and its databases. The FCC order names the main ones. A Location Validation Function checks a civic address against a geographic information system database. Once the location is validated, an Emergency Call Routing Function maps it within the boundaries of emergency response zones to pick the PSAP, and routing proxies deliver the call with its callback information.

This changes how the answering center is chosen. The legacy network looks up the address on file for a phone number. NG911 places the caller's location on a map and finds the response zone around it. For that to work, the location has to arrive with the call. The second phase of the FCC's NG911 transition rules requires providers to embed location in the call signaling, in a format called PIDF-LO or a functional equivalent.

An IP network can also carry more than a voice call. NENA notes that legacy 911 networks carry voice and little else. The FCC says NG911 "in its end state" will support "the transmission of text, photos, videos, and data to PSAPs." The phrase "end state" matters here. It describes the finished design, and each authority reaches it on its own schedule.

NG911 changes the network that delivers a 911 call. The location still starts with you and your provider, and providers have duties under both architectures.

Atlantech Online, a business phone and fiber provider based in the Washington, DC area, documents two ways to store 911 location data for its customers. With the static option, you assign an address to each phone number. Atlantech stores it and sends it to the 911 center when that number dials 911. It works the way the legacy lookup does: a number retrieves a stored address. Atlantech calls it "the simplest and most common way" to store the data, suited to a business whose phones stay at one fixed location. The static record holds a street address with no floor, suite or room number.

The dynamic option moves the location into the call. You configure the location of each phone in your network switches and Wi-Fi access points, and that information passes to Atlantech's network in PIDF-LO headers. The record updates when a phone moves within your network, and it can include the floor, suite or room. It needs network equipment that supports PIDF-LO, and Atlantech notes that a firewall or NAT device can block or alter the headers.

Suppose a school has four buildings behind one street address. Its switches and access points are configured with the building and room each one serves, and teachers carry Wi-Fi phones from room to room. A static record gives responders the same street address for every call. A dynamic record can give them the building and room, as precisely as that configuration allows. Federal rules define a dispatchable location as a validated street address "plus additional information such as suite, apartment or similar information necessary to adequately identify the location of the calling party." On a campus like that one, Atlantech's static record can't supply the extra detail, and a location configured in the network can.

PIDF-LO is also the format the NG911 rules name for the hop from a provider to the 911 network. That is a separate hop from the one Atlantech's post describes, which runs from your network to the carrier. The idea is the same on both: location travels inside the call, where the legacy network keeps it in a database keyed to a phone number.

NG911 has no national switch-on date. The FCC's rules start a clock for a provider only when a 911 authority asks. Under 47 CFR 9.31, the authority first has to certify that it "has installed and placed into operation all of the infrastructure needed to receive 911 traffic in an IP-based SIP format" and pass that traffic to its PSAPs.

In the first phase, the provider delivers 911 traffic in that IP format to delivery points the authority designates. The second phase adds the embedded location. Section 9.30 gives an interconnected VoIP provider six months to meet each phase after a valid request, and some smaller carriers get 12.

So progress varies from one place to the next. The FCC's July 2026 order says: "Many 911 Authorities have made significant progress to implement the transition to NG911." The order also describes transitional networks that "blend some legacy network components with IP-based infrastructure." Those can keep selective routers and ANI/ALI databases in the call path while the ESInet is being built, with gateways that translate between the old and new formats. The order also cites the FCC's annual 911 fee report, in which 42 states, the District of Columbia, Guam and Puerto Rico reported spending on NG911 programs during 2024.

For this reason the NG911 label says little by itself. A state can have an NG911 program and still deliver your call through a selective router. To learn what applies to your calls, ask your provider whether the 911 authority for your address has sent a Phase 1 or Phase 2 request. And check that your own location record carries the floor and suite a responder would need, because that record is used under either architecture.