6.1 Call Answering Standards & Answering Point Workflows

6.1 Call Answering Standards & Answering Point Workflows

Quick Answer: Call answering and processing performance in PSAPs and emergency communications centers is measured against two current national standards that now agree on the answering benchmark. NFPA 1225 (2022) requires 90% of emergency calls to be answered within 15 seconds and 95% within 20 seconds, transfers to be completed within 30 seconds for 90% of calls, and alarm processing for the highest-priority emergencies within 60 seconds for 90% of events. NENA-STA-020.1-2020 (updated as NENA-STA-020.2-2026) replaced NENA's old 10-second busy-hour guidance with the same 90%/15-second and 95%/20-second answering targets, and the 2026 update added ready-for-dispatch targets of 60 seconds for imminent threats and 90 seconds for other emergency calls. Answer time runs from call arrival at the PSAP (trunk seizure or SIP INVITE) until the call is answered. Abandoned calls receive verification callbacks under agency policy, and trunks are engineered to a P.01 grade of service (no more than 1% blocking in the busy hour).

---

1. National Call Answering Benchmarks: NFPA 1225 & NENA-STA-020

Public safety communications centers operate under stringent time benchmarks established by national standard-setting bodies. For the Emergency Number Professional (ENP), mastering the operational distinctions between standards issued by the National Fire Protection Association (NFPA) and the National Emergency Number Association (NENA) is vital for operational leadership, agency accreditation, and examination success.

[Incoming 9-1-1 Call Arrives at PSAP]
       │
       ├───────────────────────────────┬───────────────────────────────┐
       ▼                               ▼                               ▼
[15 Seconds]                    [20 Seconds]                    [60 Seconds]
NFPA 1225 & NENA-STA-020:       NFPA 1225 & NENA-STA-020:       NFPA 1225 alarm processing:
90% of calls answered           95% of calls answered           90% of highest-priority events

NFPA 1225: Standard for Emergency Services Communications (2022)

In 2022, the NFPA consolidated NFPA 1221 (Installation, Maintenance, and Use of Emergency Services Communications Systems) and NFPA 1061 (Public Safety Telecommunications Personnel Professional Qualifications) into NFPA 1225. Its operating benchmarks for communications centers appear in Chapter 15:

• Answering (15.4.1): Ninety percent (90%) of emergency calls shall be answered within 15 seconds, and ninety-five percent (95%) within 20 seconds.
• Transfers (15.4.2): Emergency calls that must be transferred shall be transferred within 30 seconds for 90% of calls.
• Alarm Processing (15.4.4): Processing of the highest-priority emergencies shall be completed within 60 seconds for 90% of events. The standard lists exceptions for calls that legitimately need more time, such as calls requiring EMD pre-arrival instructions, language interpretation, or TTY/text communication.

NENA-STA-020: NENA Standard for 9-1-1 Call Processing

• Current answering standard: NENA-STA-020.1-2020 states that 90% of 9-1-1 calls arriving at the PSAP shall be answered within 15 seconds and 95% should be answered within 20 seconds. It replaced the older NENA 56-005 guidance that targeted 90% within 10 seconds during the busy hour, so the 10-second figure is historical.
• Measurement: Answer time runs from the moment the call arrives at the PSAP until it is answered, and compliance is reported over regular reporting periods rather than only the busiest hour.
• 2026 update: NENA-STA-020.2-2026 keeps the 15/20-second answering targets and adds ready-for-dispatch targets: calls involving an imminent threat to life within 60 seconds, and other emergency calls within 90 seconds.

---

2. Telemetry & Objective Measurement Methodologies

Accurate compliance reporting requires rigorous, objective data capture. Historically, manual logging or telecommunicator keystrokes introduced substantial measurement error. Modern PSAPs rely on computerized Automated Call Distribution (ACD) and Management Information Systems (MIS) telemetry embedded directly within call-handling Customer Premises Equipment (CPE).

[Trunk Seizure / Ring-In] ────► [ACD Queue / Ring Delay] ────► [Console Seizure / Voice Answer]
         │                                                              │
         └────────────────── TOTAL ANSWERING TIME ──────────────────────┘
                             (Standard Benchmark Window)

The Start-of-Ringing Rule

Both standards measure answering time from call arrival at the PSAP (the start of ringing on legacy trunks) to telecommunicator pickup:

• Start of Ringing Defined: In legacy circuit-switched networks, this corresponds to the moment the incoming Central Office or Selective Router trunk seizes the PSAP line interface card and presents the first electrical ring cycle. In Next Generation 9-1-1 (NG911) SIP networks, it corresponds to the receipt of the initial SIP INVITE message at the PSAP Border Control Function (BCF) or Emergency Service Routing Proxy (ESRP).
• Telecommunicator Pickup Defined: The exact millisecond the call-taker depresses the console headset key, clicks the answer icon on the graphical user interface, or when an automated headset auto-answer connects the two-way audio path.

Operational Measurement Pitfalls

ENP candidates must identify common administrative measurement traps that skew compliance audits:

1. Measuring from CAD Entry: Initiating measurement when a call taker opens an incident record in Computer Aided Dispatch (CAD) is completely invalid. Call-handling CPE telephone answering precedes CAD incident creation by several seconds.
2. Excluding Abandoned Calls: Abandoned calls that disconnect after ringing for 10 or 15 seconds must still be analyzed in queue telemetry. If an agency only measures completed calls, true queue delays during peak spikes remain hidden.
3. Administrative PBX Ring Transfers: Transferring emergency calls across administrative internal switch lines introduces unmonitored ring delays that violate national tracking requirements.

---

3. Total Alarm Handling & Parallel Dispatch Workflows

Call answering speed is merely the first segment of emergency response. NFPA 1225 establishes strict benchmarks across the entire lifecycle of an incident, defining total Alarm Handling Time as the sum of answering, interrogation, and dispatch notification.

  t0: Network Ring-In
   │
   │  [Answering Interval: <= 15 seconds (90%)]
   ▼
  t1: Telecommunicator Answers Voice Call
   │
   │  [Interrogation & Location Verification Interval: ~30-45 seconds]
   ▼
  t2: Incident Categorized & Sent to Dispatch Queue (CAD Entry)
   │
   │  [Dispatch Decision & Unit Notification Interval: <= 15-30 seconds]
   ▼
  t3: Responding Units Alerted (Radio, Tones, Mobile Data Terminals)
   │
   └──── TOTAL ALARM HANDLING TIME (t0 to t3): <= 60 seconds (90%) ────┘

Alarm Processing Benchmarks

For the highest-priority, life-threatening events (structure fires, cardiac arrests, active assailants, violent crimes in progress):

• NFPA 1225 (15.4.4): Alarm processing shall be completed within 60 seconds for 90% of events, with listed exceptions for call types that need additional interrogation or special handling.
• NENA-STA-020.2-2026: Calls involving an imminent threat to life should be ready for dispatch within 60 seconds, and other emergency calls within 90 seconds.
• Local performance plans: Agencies set their own targets for lower-priority and non-emergency incidents; neither standard sets one national figure for routine calls.

Parallel Dispatch Workflows

To satisfy the 60-second alarm handling benchmark, modern PSAPs employ parallel dispatch (concurrent processing). In a split-function center (call-taker/dispatcher separation) or consolidated center, the call taker verifies the physical address and chief complaint within the first 20 to 30 seconds and immediately transmits the pending incident into the CAD dispatch queue. The radio dispatcher broadcasts the alarm to field units while the call taker remains on the line with the caller, conducting secondary interrogation and delivering life-saving pre-arrival instructions.

---

4. Primary vs. Secondary PSAP Transfer Workflows

In multi-agency and regional jurisdictions, a Primary PSAP is the first public safety answering point to receive the incoming 9-1-1 call directly from the selective router or ESInet. When the incident falls outside the primary agency's immediate operational scope, the call must be transferred to a Secondary PSAP (e.g., a specialized municipal fire communications bureau, an independent emergency medical dispatch center, or a state highway patrol dispatch facility).

[Incoming 9-1-1 Call]
         │
         ▼
[PRIMARY PSAP]
- Answers call within 15s
- Verifies civic location
- Identifies discipline (Law, Fire, EMS)
         │
         ├───────────────── Transfer Initiated within 30s (NFPA 1225) ─────────────────┐
         │                                                                             │
         ▼                                                                             ▼
[WARM / ANNOUNCED TRANSFER]                                                   [DATA PUSH / CAD-TO-CAD]
- Initiator stays on line                                                      - Automatic ALI push
- Introduces caller, address, chief complaint                                 - Geodetic coordinates forward
- Confirms secondary PSAP has seized line                                      - Incident remarks transfer
- Required for all high-acuity life-threats                                    - Synchronous console update

The 30-Second Transfer Initiation Benchmark

NFPA 1225 (Section 15.4.2) expects emergency calls that require transfer to be transferred within 30 seconds for 90% of calls, so the need for transfer should be identified early in the call.

Technical Handoff Modalities

• Selective Transfer: In legacy E9-1-1 networks, pressing a dedicated speed-dial button on the call handling console signals the Selective Router to transfer the voice circuit and forward the caller's Automatic Number Identification (ANI) to the secondary PSAP.
• Warm (Announced) Transfer: The initiating telecommunicator stays on the line, introduces the caller, relays the verified address, caller name, and nature of the emergency, and provides the CAD incident number before disconnecting. Warm transfers are mandatory for high-priority medical, fire, or violent in-progress incidents to prevent critical information loss.
• Blind (Unannounced) Transfer: The initiating call taker immediately connects the caller to the secondary agency without speaking to the receiving dispatcher. Blind transfers are strongly discouraged in public safety and prohibited in life-threatening calls.
• Conference Transfer (Bridged Transfer): A three-way audio bridge where both telecommunicators and the caller are connected simultaneously, allowing mutual interrogation without dropping background context.
• Data Push Integration (CAD-to-CAD / NG911 SIP): Modern CAD-to-CAD interfaces (using the APCO/NENA Emergency Incident Data Document standard and NENA's Emergency Incident Data Object) and NG911 SIP INVITE messaging automatically push the caller's geodetic location, civic address, and active telecommunicator remarks directly into the receiving agency's CAD workstation simultaneous with the voice transfer.

---

5. Abandoned Call Handling Protocols & Unverified Disconnects

An abandoned call occurs when an incoming caller disconnects after the call has seized a network trunk and initiated ringing at the PSAP, but before a telecommunicator answers and establishes two-way communication.

[Abandoned Call Arrives at PSAP]
       │
       ▼
[CPE Captures ANI / ALI]
       │
       ▼
[Immediate Telecommunicator Verification Callback]
       │
       ├───────────────────────────────┬───────────────────────────────┐
       ▼                               ▼                               ▼
[Caller Answers & Verbalizes]   [Unanswered / Busy / Voicemail] [Open Line / Distress Sounds]
       │                               │                               │
  Positive Safety Verification    Check Prior Call History &      Mute Call-Taker Audio,
  Mandated (No Rushed Clear)      Address Records; Dispatch Law   Listen 15-30s; Immediate
                                  Enforcement if Address Exists   Priority Police Dispatch

Abandonment Rates & Queue Dynamics

Agencies track the abandoned call rate as a key queue-health metric and set local targets, often a low single-digit percentage of incoming volume. Abandonment rises sharply as wait times grow. Callers hanging up under stress frequently redial immediately, creating duplicate incoming calls that compound queue congestion.

Mandatory Verification Callbacks

Agency standard operating procedures, informed by NENA call processing guidance, typically require verification callbacks on abandoned 9-1-1 calls:

1. Immediate Outdial: The telecommunicator must immediately query the incoming record's Automatic Number Identification (ANI) and place an outgoing verification call. Agency policies typically mandate one or two immediate redials if the line is initially busy or unanswered.
2. Voicemail Protocol: If the callback reaches voicemail, the telecommunicator must leave a scripted, professional message stating: "This is the 9-1-1 Emergency Communications Center calling back to verify a 9-1-1 disconnect from this number. If you have an emergency, please dial 9-1-1 immediately. If this was an accidental call, please call our administrative number to confirm you are safe."

Open Line & Background Listening Protocols

If an abandoned call connects on callback as an open line, or if an incoming 9-1-1 call presents as an open line without verbal interaction:

• Acoustic Surveillance: The telecommunicator must immediately mute their room microphone to eliminate center background noise and actively listen to the open line for 15 to 30 seconds.
• Distress Indicators: Personnel listen for whispers, scuffling, physical impact sounds, domestic disputes, crying, labored or agonal breathing, weeping, or vehicle engine sounds.
• Audio Challenge: If no sounds are heard, the telecommunicator speaks clear challenges: "9-1-1, what is your emergency? If you cannot speak, tap your phone or press any key."

Cellular Pocket Dials & Accidental Calls

With modern smartphones and smartwatches, accidental dials (pocket dials, fall detection triggers, or crash alerts) constitute a significant percentage of 9-1-1 traffic:

• Positive Safety Verification: If the caller answers and insists the call was accidental, the telecommunicator must NOT simply say "Okay" and hang up. The telecommunicator is required to execute a positive safety verification: "Can you confirm your current address, and can you confirm that you are safe and do not require police, fire, or ambulance assistance?"
• Anti-Coercion Protocol: The call taker must listen to the tone and inflection to ensure the caller is not being coerced by an assailant standing nearby.

Law Enforcement Dispatch on Unverified Disconnects

If the verification callback is unanswered, encounters a continuous busy signal, or reaches an open line, agency policy governs field response:

• When a verified civic address (wireline ALI) or a high-confidence wireless geodetic location (Phase II or Device-Based Hybrid Location) is available, standard operational doctrine mandates dispatching a law enforcement unit to conduct a physical welfare check.
• If the call originated from an uninitialized mobile device (9-1-1-only phone lacking a callback number) or yields only a broad cell tower centroid covering several square miles, an in-person field check may be operationally impossible without further location refinement.

---

6. Telephony Traffic Engineering: Grade of Service (GoS) P.01

Before a telecommunicator can answer an emergency call within 15 seconds, the public switched telephone network (PSTN) and PSAP ingress trunks must possess sufficient physical capacity to deliver the call without blocking.

The P.01 Grade of Service Benchmark

In public safety telecommunications engineering, network trunk groups are mandated to meet a P.01 Grade of Service (GoS):

• Definition: During the Average Busy Hour (ABH), no more than one call out of every 100 incoming emergency calls (1%) may encounter a trunk busy signal (blocking) due to insufficient network facilities.
• Distinction from Answering Standards: ENP candidates must never confuse P.01 Grade of Service with call answering benchmarks. P.01 is a telephony facility capacity metric calculated mathematically, whereas the 15-second benchmark is an operational human staffing metric.

Erlang B Traffic Modeling

Trunk group provisioning is engineered using the Erlang B loss model, which calculates the probability of blocking under the assumption of random Poisson call arrivals and blocked calls cleared:

$P_b = B(c, A) = \frac{\frac{A^c}{c!}}{\sum_{k=0}^{c} \frac{A^k}{k!}}$

Where:

• $P_b$ is the probability of blocking ($0.01$ for P.01 GoS)
• $c$ is the total number of dedicated trunks in the trunk group
• $A$ is the total offered traffic intensity expressed in Erlangs ($A = \lambda \times h$, where $\lambda$ is arrival rate per hour and $h$ is average call holding time in hours)

Engineering Example: If a 9-1-1 authority experiences 60 calls in the busy hour with an average holding time of 3 minutes (180 seconds), the offered traffic load is: $A = 60 \times \left(\frac{3}{60}\right) = 3.0 \text{ Erlangs}$ To achieve a standard P.01 Grade of Service (blocking $\le 0.01$) for 3.0 Erlangs of traffic, Erlang B mathematical tables dictate that the PSAP must provision a minimum of 8 dedicated trunks. Provisioning only 4 or 5 trunks would produce an unacceptable blocking probability exceeding 10% to 15%, resulting in citizen busy signals during emergencies.

---

7. Operational Traps & ENP Exam Watch

• The 10-Second Figure Is Outdated: NFPA 1225 and the current NENA-STA-020 both use 90% answered within 15 seconds and 95% within 20 seconds. The old NENA 56-005 target of 90% within 10 seconds during the busy hour has been replaced; treat it as history, not the current standard.
• Alarm Handling vs. Answering Time: Answering time ($t_0$ to $t_1$) is only the interval until pickup (15 seconds). Total Alarm Handling Time ($t_0$ to $t_3$) includes answering, address verification, interrogation, and unit dispatch, which NFPA 1225 sets at $\le 60$ seconds for 90% of the highest-priority events.
• P.01 is Erlang B, Staffing is Erlang C: Network trunk sizing uses Erlang B (calls encountering busy circuits drop or overflow). Telecommunicator staffing calculations use Erlang C (calls are held in an ACD queue until a human call taker becomes available).
• Mandatory Callback on Abandoned Calls: Never accept an automated system closure for an abandoned 9-1-1 call. If a call disconnects, an immediate verification callback is required by operational standard.