Trust & Security

E911 (Enhanced 911) and the Laws Behind It

E911 is the Enhanced 911 emergency-services system in North America: dial 911, get connected to the nearest Public Safety Answering Point (PSAP), and have the dispatcher automatically see your callback number and dispatchable street address. For traditional landlines this 'just works' — the address is tied to the copper pair. For VoIP it is a hard problem the FCC has been legislating since 2005, and DIDHub solves it by letting you register a per-DID dispatchable location for any phone number on the platform.

What 'Enhanced' actually means

Plain 911 (1968 onward) just routed the call to the nearest sheriff. The dispatcher saw nothing — the caller had to read out their address while panicking. E911 adds two automatic data feeds:

ANI (Automatic Number Identification): the calling number, automatically displayed at the PSAP.
ALI (Automatic Location Identification): the dispatchable address tied to that number, fetched in real-time from the ALI database during call setup.

So when a 911 call comes in, the dispatcher's screen shows: +1 415 555 1234 — 1455 Market St, Floor 22, San Francisco CA 94103. They can dispatch police, fire, or EMS without the caller saying a word.

How the call actually routes

Caller dials 911.
Originating carrier recognizes the digits, queries an emergency-routing function (Selective Router on legacy 911, or ESRP on NG911) to find the right PSAP based on the caller's location.
Carrier delivers the call (with ANI) to the PSAP.
PSAP's CAD (Computer-Aided Dispatch) system queries the ALI database with the ANI — gets back the address.
Dispatcher sees ANI + ALI, talks to caller, dispatches first responders.

Total setup time: typically <3 seconds.

The legacy stack vs NG911

	Legacy E911	NG911 (Next Generation)
Transport	TDM trunks, MF signaling	SIP over IP (ESInet)
Routing	Selective Router by NPA-NXX	ESRP + LoST queries by location
Location format	10-digit ANI + ALI flat record	PIDF-LO (RFC 4119) civic + geo
Data delivery	Voice + ANI only	Voice + text + image + video + telematics
Standards body	NENA + ATIS	NENA i3 (NENA-STA-010)
FCC mandate	2005 VoIP E911 Order	FCC NG911 transition orders, ongoing

As of 2026, ~70% of US PSAPs are NG911-capable. The transition continues. NENA i3 (the NG911 reference architecture) is the SIP-based replacement for the entire legacy 911 stack.

The laws (US) — what each one actually requires

Law / Order	Year	What it requires
Wireless Communications & Public Safety Act (911 Act)	1999	Designated 911 as the universal emergency number nationwide. Mandated wireless carriers to deliver E911.
FCC VoIP E911 Order (FCC 05-116)	2005	Required all interconnected VoIP providers (those reaching the PSTN) to provide E911. Customers must register a service address; provider must route to the right PSAP. Carriers cannot disconnect service for non-payment of E911 fees alone.
NET 911 Act	2008	Gave VoIP providers legal access to the same trunks and ALI databases that incumbent carriers use, removing artificial gatekeeping.
Kari's Law (Pub. L. 115-127)	Signed 2018, effective Feb 16, 2020	MLTS (multi-line telephone systems — office PBXs, hotels) must allow direct 911 dialing without a prefix (no more "dial 9 first"). Must also notify a designated person on-site (e.g. front desk) when a 911 call is placed.
RAY BAUM's Act § 506	Signed 2018, FCC rules effective Jan 6, 2021 (fixed) / Jan 6, 2022 (non-fixed)	MLTS calls to 911 must convey a dispatchable location (street + room/floor/suite) sufficient for first responders to find the caller, not just a building address. Applies to fixed AND non-fixed (mobile, softphone) endpoints.
FCC NG911 Section 6 Report	2021-ongoing	Mandates carrier readiness to deliver to NG911-capable PSAPs over IP/SIP per NENA i3. State-by-state rollout funded by federal grants.
State-level: NY S.40, IL HB 358, TX SB 788, CA AB 1018	Various 2017-2022	State-specific Kari's Law / dispatchable-location implementations. Many states have stricter rules than federal.

What 'dispatchable location' means under RAY BAUM's Act

The FCC defines dispatchable location as 'the street address of the calling party, plus additional information such as room number, floor number, or similar information necessary to adequately identify the location of the calling party.' Bare 'building 1455 Market St' is not enough for a 30-story office building — you need floor + suite/room as well.

The rule applies to:

Fixed MLTS endpoints (a desk phone wired to a specific desk): location is the static dispatchable address. Effective Jan 6, 2021.
Non-fixed MLTS endpoints (laptop softphone, mobile app): location must be conveyed at the time of the call, with one of three approaches: (a) automated location, (b) end-user provided, or (c) default location with carrier escalation. Effective Jan 6, 2022.

How VoIP carriers actually deliver E911

Below the surface, every VoIP carrier (DIDHub included) connects to one of a handful of E911 service providers that operate the carrier-grade interconnect to PSAPs:

Bandwidth.com
Intrado / Lumen (formerly West)
Comtech (911-LBS)
RedSky Technologies (Cisco)

These providers maintain the LIS/ALI database, run selective-router and ESRP interconnects to ~6,000 US PSAPs, and accept dispatchable-location updates via SOAP/REST APIs. DIDHub provisions and updates location data on your behalf via these providers; you deal only with DIDHub.

The MSAG: why your suite number matters

The Master Street Address Guide (MSAG) is the canonical address database each PSAP uses. Every dispatchable location must be MSAG-validated before it can be provisioned to ALI — otherwise the address is rejected and 911 calls fall back to a default routing (often the carrier's NOC, with a hold time, which costs lives).

MSAG validation rejects:

Non-existent street names (typos, abbreviations).
Non-existent street numbers (15555 Main St when 15555 doesn't exist).
Wrong city/county for a ZIP.
PO boxes (not dispatchable).
Apartment numbers in buildings that don't have them.

DIDHub's address API runs MSAG validation in real-time. If your address is rejected, the dashboard shows the canonical MSAG version and lets you accept or correct.

Setting up E911 on a DIDHub DID

Every US/Canada DID on DIDHub can be enabled for 911 calling. The flow:

Dashboard → Number → E911. Click Register dispatchable location.
Enter the end-user's address. Required fields: street number, street name, street type, unit/suite/floor/room (if applicable), city, state, ZIP.
DIDHub runs MSAG validation. Address is normalized; you accept the canonical version.
Optional: enter the end-user's name and callback number override.
Save. DIDHub provisions to the LIS/ALI database within ~5 minutes (NG911 fabric) or ~24 hours (legacy ALI).
Activation status moves from Pending → Provisioned → Active. Once Active, 911 dialing from that DID is live.

# API equivalent
curl -X POST https://api.didhub.io/v1/numbers/+15551234567/e911 \
  -H "Authorization: Bearer $DIDHUB_TOKEN" \
  -d '{
    "street_number": "1455",
    "street_name": "Market",
    "street_type": "St",
    "unit_type": "Suite",
    "unit_value": "2200",
    "city": "San Francisco",
    "state": "CA",
    "zip": "94103",
    "caller_name": "Alice Example",
    "callback_number": "+15551234567"
  }'

Per-call location override (for nomadic / softphone users)

For users moving between offices, working from home, or on a softphone, the registered DID address may be wrong on a given day. RAY BAUM's Act allows per-call location override:

End-user app/PBX supplies a current dispatchable location at registration or call time.
DIDHub accepts location updates via API or in-band (PIDF-LO in SIP INVITE Geolocation header, RFC 6442).
For 911 calls, DIDHub uses the most-recent location. If no override, falls back to the registered DID address.

# Update location at user login (typical for softphones)
PUT /v1/numbers/+15551234567/e911/current-location
PIDF-LO options accepted: civic-address, geodetic (lat/lon)

# Or include Geolocation header in the SIP INVITE for that call:
INVITE sip:[email protected] SIP/2.0
Geolocation: <cid:loc-1>;routing-allowed=yes
Content-Type: multipart/mixed;boundary=...

--boundary
Content-Type: application/sdp
...
--boundary
Content-Type: application/pidf+xml
Content-ID: <loc-1>

<presence ...>
  <tuple id="t1"><status>
    <geopriv><location-info><civicAddress>
      <country>US</country><A1>CA</A1>
      <A3>San Francisco</A3><HNO>1455</HNO>
      <RD>Market</RD><STS>St</STS>
      <FLR>22</FLR>
    </civicAddress></location-info></geopriv>
  </status></tuple>
</presence>

Kari's Law: direct 911 + on-site notification

If you operate a multi-line phone system (PBX, hosted PBX, hotel system) on US territory, you must:

Allow direct 911 dialing — no prefix ("dial 9 first") required.
Notify a designated on-site person (front desk, security, building manager) whenever a 911 call is placed. Notification must include caller's extension and dispatchable location.

DIDHub provides Kari's Law notification webhooks. Configure a target email + webhook URL per trunk. On every 911 call, both fire within seconds.

{
  "event": "e911.call_placed",
  "timestamp": "2026-04-27T14:23:01Z",
  "did": "+15551234567",
  "caller_name": "Alice Example",
  "extension": "2204",
  "dispatchable_location": "1455 Market St, Suite 2200, San Francisco CA 94103",
  "psap_routed_to": "San Francisco PSAP (Brisbane CA)"
}

Default location and 'no location' calls

Even after RAY BAUM's Act, some calls arrive with no usable location: a softphone whose user never set an address, a brand-new DID with no provisioning, an emergency on a temporary hot-spot. The FCC requires carriers to handle these via:

Default location: a fallback address (usually the customer's HQ) is used.
National Routing & Location Service (NRLS): the carrier escalates the call to a national emergency call center, which gathers location verbally and bridges to the right PSAP.

DIDHub's default behavior: if no per-call location and no registered location, route to the NRLS via the underlying provider (Bandwidth/Intrado), which will route to the right PSAP after an operator-assisted location prompt.

Compliance fees

911 service is funded by per-line fees collected by carriers and remitted to state E911 funds. Fees vary by state ($0.20-$3.00 per DID per month). DIDHub itemizes E911 fees on your invoice; we do not mark them up. The fee schedule by state is published in the dashboard under Billing → E911 Fee Schedule.

Note: per FCC rules, providers may not disconnect service for non-payment of E911 surcharges alone — only for non-payment of the underlying service.

International equivalents

Region	Number	Notes
EU + EEA	112	Universal across all EU member states (Directive 2018/1972). Eircall + AML (Advanced Mobile Location) deliver GPS coordinates to PSAPs.
UK	999, 112	112 also accepted; both route through BT 999 service.
Israel	100 (police), 101 (medical), 102 (fire)	Separate numbers per agency. No unified emergency number.
Australia	000 (also 112 from mobiles)	112 mandated for GSM compatibility.
Japan	110 (police), 119 (fire/ambulance)	Two separate numbers.
India	112 (unified, since 2019)	Replaced 100/101/102.
Brazil	190 (police), 192 (medical), 193 (fire)	Separate; some states accept 911 due to American influence.
Mexico	911	Unified since 2017.
South Africa	10111 (police), 10177 (medical)	Separate numbers; 112 from mobile.
UAE	999 (police), 998 (medical), 997 (fire)	Separate numbers.

DIDHub supports E112 in EU/UK and equivalent emergency calling in 35+ countries. The setup pattern is identical: register a dispatchable location per DID; the in-country provider handles routing.

Common gotchas

Soft-launching with E911 disabled: tempting in dev, dangerous in production. Customers expect 911 to work. Enable from day one.
Forwarding 911 to a fax line: some PBX dialplans intercept 911 thinking it's a custom code. Always test 911 routing before going live.
911 from a DID that has no MSAG-valid address: falls back to NRLS — adds 30+ seconds to dispatch time. Always provision the address before activating the DID.
Confused-call-back loops: if your callback number is the company main line, the dispatcher's call-back goes to a receptionist, not the actual caller. Set callback to the real DID, not the main number.
Hotels / multi-tenant buildings: RAY BAUM's Act requires room-level dispatchable location. A single building address for 200 rooms is NON-COMPLIANT and a fineable offense.
International soft-clients: a softphone using a US DID from outside the US cannot reach 911 — the call would route to the registered US address but the user is in another country. Enforce geo-fencing on softphones.

Testing 911 (without bothering a PSAP)

The FCC and PSAP operators have a special process for testing 911 routing without dispatching first responders:

Dial 933 from the DID. This is the E911 self-test number — reads back the registered ANI and ALI to the caller as text-to-speech, without involving a real PSAP.
If 933 is not provisioned, schedule a coordinated test with the PSAP via the carrier's emergency-services contact.

933 is the right way to validate. Never test by dialing real 911 unless coordinated with the PSAP — misuse of 911 is a misdemeanor in most states.

References

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