6.4 PSAP Types & 9-1-1 Call Handling Equipment
Key Takeaways
- A primary PSAP receives 9-1-1 calls directly from the network, a secondary PSAP receives calls transferred from a primary PSAP, and an alternate PSAP receives calls routed to it when the primary cannot answer.
- Consolidated PSAPs operate as one combined organization, co-located PSAPs share a building while keeping separate operations, and virtual PSAPs connect staff at different locations on shared systems.
- Legacy PSAP equipment used separate ANI controllers, ALI controllers, ANI and ALI displays, and system controllers, protected by an uninterruptible power supply.
- Modern call handling equipment integrates telephony, location, text, and CAD on intelligent workstations using computer telephony integration (CTI), with ACD for call distribution and MIS for performance reporting.
- Call handling equipment can be on-premises, hosted at a shared site, or delivered as Call Handling as a Service (CHaaS), each with different cost, resilience, and contract considerations.
6.4 PSAP Types & 9-1-1 Call Handling Equipment
Quick Answer: A primary PSAP receives 9-1-1 calls directly from the 9-1-1 network; a secondary PSAP receives calls transferred from a primary PSAP; an alternate PSAP takes calls routed to it when the primary cannot. PSAPs may serve one jurisdiction or many, and they may be consolidated (one combined operation), co-located (separate agencies sharing a building), or virtual (staff in different places working as one logical PSAP on shared systems). The equipment that answers 9-1-1 calls, call handling equipment (CHE), evolved from separate ANI and ALI controllers and displays to integrated intelligent workstations using computer telephony integration (CTI), automatic call distribution (ACD), management information systems (MIS), gateways, and uninterruptible power. CHE can be on-premises, hosted, or delivered as Call Handling as a Service (CHaaS).
1. Types of PSAPs
| PSAP Type | Definition | Example |
|---|---|---|
| Primary PSAP | The PSAP to which the selective router or ESRP delivers 9-1-1 calls first | A county 9-1-1 center that answers all 9-1-1 calls in the county |
| Secondary PSAP | A PSAP that receives calls transferred from a primary PSAP, often to dispatch a specific discipline | A fire and EMS dispatch center that takes transferred medical calls |
| Alternate PSAP | A PSAP that receives calls routed to it when the primary is busy, evacuated, or out of service | A neighboring county that takes overflow or evacuation traffic |
| Single-jurisdiction PSAP | Serves one city, county, or agency | A municipal police department PSAP |
| Multi-jurisdiction PSAP | Serves several jurisdictions under agreements | A regional center serving a county and its cities |
| Consolidated PSAP | Formerly separate PSAPs or dispatch functions merged into one organization | A regional emergency communications district |
| Co-located PSAP | Separate agencies share a building (and often infrastructure) but keep separate staff, governance, or operations | County sheriff and city police dispatch working on the same floor |
| Virtual PSAP | Telecommunicators at different physical locations work as one logical PSAP on shared or hosted systems | Positions at two sites, plus backup positions, all on one hosted CHE and CAD |
Primary and Secondary PSAP Considerations
- Transfers cost time: Every transfer adds delay and a chance of losing information, so many regions consolidate call-taking or use incident data sharing (EIDO and CAD-to-CAD links) to speed handoffs (6.1 and 7.2).
- Wireless calls: Wireless calls often reach a primary PSAP chosen by cell sector or device location and are transferred when the caller is actually in another jurisdiction.
Consolidation Models
Consolidation can be physical (one building), functional (shared call-taking with separate dispatch), or virtual (shared systems across several sites). Governance, funding, and labor considerations are covered in 11.1.
Virtual PSAPs
NENA's information document on Virtual PSAP Management (NENA-INF-025) describes PSAPs whose positions are geographically distributed but share call handling, CAD, and radio resources. Benefits include resilience (positions survive the loss of one building), more flexible staffing (including backup or remote positions), and shared costs. Challenges include cybersecurity for remote positions, CJIS compliance, supervision and team cohesion, radio console connectivity, and clear policies for remote work environments.
2. Legacy PSAP 9-1-1 Equipment
In legacy E9-1-1, a PSAP's customer premises equipment (CPE) was often assembled from separate components:
| Component | Function |
|---|---|
| ANI controller | Decodes the calling number delivered on CAMA trunks and passes it to the ANI display and ALI controller |
| ANI display | Shows the caller's telephone number (and trunk information) to the telecommunicator |
| ALI controller | Uses the ANI to query the ALI database over data circuits and sends the response to the correct position |
| ALI display | Shows the caller's address, class of service, ESN, and responding agencies |
| System controller | Manages trunk and line appearances, transfers, and conferencing across positions |
| Uninterruptible power supply (UPS) | Keeps CPE, logging, and critical systems running through power disturbances until the generator carries the load |
Modern systems combine these functions in software, but the exam still expects you to know what each component did.
3. Modern Call Handling Equipment (CHE)
Intelligent Workstations and CTI
Intelligent workstations bring telephony, ALI or NG9-1-1 location, text and TTY, mapping, and CAD onto one PC-based position. Computer telephony integration (CTI) links the phone system to software, so answering a call can automatically fill CAD with ANI/ALI data, open the map at the caller's location, and log the event.
Automatic Call Distribution (ACD)
An ACD distributes incoming calls to available telecommunicators using rules (longest idle, skills, or priority), queues calls when every position is busy, and can play recorded messages on administrative lines. ACD data feeds reports such as answer times and abandoned calls.
Management Information Systems (MIS)
MIS collects call records from the CHE: call volume by hour, answer time, talk time, abandoned calls, transfers, and position activity. PSAPs use MIS data for NENA-STA-020 and NFPA 1225 performance reporting, staffing studies (15.1), and state 9-1-1 program reports. Time synchronization (7.3) matters so that MIS, CAD, and recorder timestamps agree.
Gateways
Gateways translate between technologies. A Legacy PSAP Gateway (LPG) lets non-IP CHE receive NG9-1-1 calls, analog gateways connect TTYs and administrative lines to IP systems, and radio gateways connect consoles to radio systems (4.3 and 5.2).
CHE Deployment Models
| Model | Where the Core Equipment Lives | Advantages | Considerations |
|---|---|---|---|
| On-premises | Servers in the PSAP's own equipment room | Local control; some local functions continue if outside links fail | Capital cost, local IT staffing, duplicate equipment for the backup site |
| Hosted / remote | Servers at a shared host site (often a state, regional, or vendor data center) serving several PSAPs | Shared cost, easier backup positions, centralized maintenance | Depends on diverse network links and shared-system governance |
| Call Handling as a Service (CHaaS) | Vendor-operated, often cloud-based service paid by subscription | Lower up-front cost, frequent updates, easy scaling | Service-level agreements, cybersecurity and CJIS terms, data ownership, exit planning |
NENA's PSAP equipment standard (NENA-STA-027) and NENA's NG9-1-1 PSAP requirements document (NENA-REQ-001) describe the functions that call handling systems should support as PSAPs move to NG9-1-1.
4. Supporting Systems at the Position
- Power: UPS plus generator protection for the entire position chain (12.1).
- Recording: Logging recorders capture calls, radio, and text (7.3).
- Time synchronization: Master clocks align CHE, CAD, recorders, and MIS (7.3).
- TTY, RTT, and text: Integrated at each call-taking position (6.2).
- Radio consoles and CAD: Covered in Chapters 5 and 7.
5. Operational Traps & ENP Exam Watch
- Secondary Is Not Alternate: A secondary PSAP receives transferred calls; an alternate PSAP receives calls routed to it when the primary cannot answer.
- Co-Located Is Not Consolidated: Co-located agencies share a building but remain separate; consolidated agencies operate as one organization.
- ANI vs. ALI Controllers: The ANI controller decodes the number; the ALI controller uses that number to query the database.
- ACD vs. MIS: ACD distributes and queues calls in real time; MIS reports on call statistics afterward.
- CHaaS Lives in the Contract: With CHaaS, service levels, security obligations, and data ownership depend on the contract terms (Chapter 14).
A 9-1-1 call is answered at the county's primary PSAP and then handed off to the city fire department's dispatch center for response. How is the fire dispatch center classified?
What distinguishes a co-located PSAP arrangement from a consolidated PSAP?
In a legacy E9-1-1 PSAP, which component used the caller's telephone number to query the ALI database and deliver the address to the correct position?