Someone on the third floor dials 911. The ambulance heads for your street address, and your street address is a 200,000-square-foot building with four entrances. The two groups who can meet the paramedics at the right door, the front desk and the security team, do not yet know the call happened.

On-site 911 notification solves that problem, and since February 16, 2020, federal law requires it. Kari’s Law covers every multi-line telephone system (MLTS) installed, manufactured, or upgraded after that date: the system must support direct 911 dialing, with no “dial 9 for an outside line” first, and must send a notification to a central on-site location when someone dials 911. RAY BAUM’S Act adds the dispatchable-location requirements on top, with fixed MLTS devices covered as of January 2021. If your PBX serves an office, school, hotel, or warehouse in the US, this applies to you.

The encouraging part for anyone running an older Cisco, Avaya, Mitel, Panasonic, 3CX, or Asterisk system: the notification half of compliance can come from data your PBX already produces.

The four things the front desk needs in the first two minutes

A notification that says “a 911 call occurred” is close to useless. To help at the door when the ambulance pulls up, the alert must answer four questions:

  1. Which extension dialed, with the caller’s name from your directory if you have one.
  2. The extension’s physical location: building, floor, room or cubicle area. This piece takes preparation, because someone has to maintain an extension-to-location table and update it when people move desks.
  3. The call’s start time, so security knows whether this is happening now or happened ten minutes ago.
  4. A callback number for the extension, because dispatchers and on-site teams may both need to reach the caller back.

Aim for delivery within one to two minutes of the call. Emergency responders arrive in single-digit minutes in most areas; an alert that lands in fifteen serves the audit trail and misses the event.

Detecting 911 calls in call records

Every PBX on the list above emits a call record (CDR or SMDR) for each call, including the dialed digits, the originating extension, and a timestamp. Detection is pattern matching on the dialed-number field as records stream out of the system:

  • 911 on its own
  • 9911 and 8911: trunk-access prefixes still configured on thousands of systems (more on these below)
  • 933 where your VoIP provider offers it, so tests get flagged the same way real calls do

The catch is when the record becomes available. Some systems emit SMDR at call start or in near real time over a serial or IP stream; Avaya IP Office and most Panasonic systems behave this way, which is ideal. Others write the CDR at call end, or batch records to a file (Cisco CUCM pushes CDR flat files on a schedule of about one minute). Know which behavior your PBX has, because it sets the floor on your notification speed. A streaming SMDR feed gets you alerts inside a minute; a system that batches every 15 minutes needs reconfiguring before it can support compliance-grade notification.

Whatever reads the records then joins the extension against your location table and fires the notifications. That is the architecture behind PBXDom’s emergency 911 alerting: a small collector reads the CDR/SMDR stream, and the cloud side does the matching and delivery within one to two minutes of the call.

Pick notification channels people see

Kari’s Law requires notification to a location where someone will see or hear it. Use more than one channel, because the front desk steps away and email sits unread:

  • Email: the always-on record, and not enough by itself.
  • SMS: the workhorse. Send to the front desk phone, the security supervisor, and the facilities manager at the same time.
  • Automated voice call: the channel that interrupts. A call that speaks “911 dialed from extension 4172, third floor east” gets attention email cannot, above all from after-hours security staff.
  • Slack or Teams channel: a dedicated #emergency channel gives the whole response team one shared timeline of the event.
  • Zapier or webhooks: for anything custom, such as lighting a beacon at the security desk or opening a ticket.

Skip escalation order and send to all channels at once. This is the one alert where redundancy beats tidiness.

Run a safe test

Do not test by picking up a phone and dialing 911 unannounced. Two safe options:

933. Several VoIP carriers and E911 service providers operate 933 as a test number: it answers with the calling number and the address on file, exercising your dial plan and your alerting without touching a dispatcher. Check whether your carrier supports it.

A coordinated test with your PSAP. Call your local dispatch center’s non-emergency administrative line, explain you need to validate MLTS 911 routing, and schedule a window. Dispatchers field these requests as a matter of routine and will confirm the address and callback number they see. Stay on the line and state that it is a test. Repeat the exercise after each PBX upgrade or carrier change.

Either way, verify the full chain: the call routed, the dispatcher saw the right location, and each notification channel fired within your target time.

The gaps that bite

Three problems show up over and over in real deployments:

Trunk-access prefixes. Kari’s Law mandates that plain 911 works, but decades of muscle memory mean people still dial 9-911 under stress. Configure the PBX so both complete, and detect both patterns in your alerting. A 9911 in the CDR is as real an emergency as a 911.

Remote workers on softphones. A VPN-connected softphone registered to your PBX may send its 911 call out your office trunks, presenting the office address for someone sitting at home. In 2021, with a large share of staff still remote, this is the most dangerous gap on the list. Make sure remote endpoints have their own E911 treatment, and that your alert identifies the device as remote so the front desk doesn’t search the building for someone in another city.

Stale location data. The extension-to-location table decays with each desk move it misses. Put it in the move-add-change checklist, and audit it once a quarter.

Wrapping up

None of this requires replacing the PBX. If your system can emit call records (and every Cisco, Avaya, Mitel, Panasonic, 3CX, or Asterisk/FreePBX system can, including end-of-life models), you can have compliant, multi-channel 911 notification running this week. PBXDom’s collector installs in about 15 minutes, watches the record stream for emergency patterns, and delivers email, SMS, automated voice, Slack, and Zapier alerts with the extension and location details filled in. The free 14-day trial is long enough to set it up and run a coordinated test with your PSAP. Start at onboarding.