Direct answer
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A public safety answering point, or PSAP, is the 911 center designated to receive emergency calls and route them to emergency services personnel. Your phone company doesn't answer a 911 call. It routes the call to an emergency answering point that serves your location.
Under the FCC's definition, a PSAP receives the 911 call and gets it to emergency services personnel. The center that answers can dispatch responders itself, or it can transfer the call to another center that does, which is where the primary and secondary labels come from.
A PSAP doesn't have to be a single building. The word in the rule is "designated," and it describes a role. NENA, the association that writes 911 standards, defines a PSAP as "a physical or virtual entity where 9-1-1 calls are delivered by the 9-1-1 Service Provider." Its glossary includes a consolidated PSAP, where several public safety agencies operate as a single 911 entity. It also includes a virtual PSAP, where the call takers work from different places and connect over an IP network. NENA ties that model to Next Generation 911 features or network-hosted PSAP equipment.
The difference between a primary and a secondary PSAP is the order in which they get the call. NENA defines a primary PSAP as one that 911 calls are routed to directly. A secondary PSAP is one that receives calls transferred from a primary.
North Carolina's 911 Board states the same split in terms of the work each one does. A primary PSAP is "the first point of reception of a 911 call by a public safety agency." A secondary PSAP can receive the voice and data of a 911 call transferred from a primary, and it completes the process by dispatching police, ambulances, firefighters or other responders.
The Board's statewide list shows how that looks in one county. In Alamance County, Alamance County Central Communications is listed as a primary PSAP, and the Burlington Police Department is listed as a secondary. So the county has both kinds: a center classed as a first point of reception and a police department classed as one that takes transferred calls.
That means the person who answers a 911 call and the person who sends the police car can sit in different centers.
The kinds of answering point
| Answering point | What it is | Defined by |
|---|---|---|
| Primary PSAP | Receives 911 calls routed to it directly | NENA |
| Secondary PSAP | Receives 911 calls transferred from a primary PSAP | NENA |
| Alternate PSAP | Receives calls when the primary PSAP is unable to | NENA |
| Statewide default answering point | Designated by the state to receive 911 calls for the whole state, or for the parts no local PSAP serves | FCC rules |
| Appropriate local emergency authority | Not officially designated a PSAP, but able to receive 911 calls and dispatch responders or relay the call | FCC rules |
Where no local PSAP serves an area, a state can designate a default answering point for it. The FCC's rules also recognize that a police department, sheriff, fire department or emergency medical provider can receive 911 calls and dispatch without holding the PSAP designation.
A 911 call is routed by the caller's location. For internet phone service, which has to connect 911 calls, the FCC's E911 rule requires the provider to send the call, the calling number and the location to the PSAP "that serves the caller's dispatchable location." Dispatchable location means a validated street address, plus a suite, apartment or similar detail where that's needed to find the caller.
Location is used twice on the way. It decides which PSAP gets the call, and then it tells the call taker where to send help. Microsoft's Teams documentation describes both uses. The emergency service provider uses the location to pick the appropriate PSAP and route the call there. It then gives the PSAP dispatcher the caller's location.
Atlantech Online, a business phone provider in Silver Spring, Maryland, describes E911 the same way from the provider's side. E911 identifies the caller's location and routes the call to the appropriate local PSAP. It then gives the PSAP that location, and Atlantech uses its own address, 1010 Wayne Avenue in Silver Spring, as the example.
This is why the address on file with a VoIP provider matters at the PSAP's end. With Atlantech's static option, the address assigned to a phone number is stored and sent to the 911 call center when that number dials 911. Atlantech warns that if you move the phone and don't update the address, the 911 center receives the wrong location.
An Atlantech customer can hear the address on file by dialing 933, one of the steps in registering a VoIP phone for 911.
A PSAP can only work with the information that arrives, and two things can reduce it.
The first is the PSAP's own capability. The E911 rule says that if a PSAP isn't capable of receiving and processing the calling number or the location, the provider doesn't have to send the information that PSAP can't handle. The call still has to be delivered.
The second is the detail in the record. Atlantech says its static option doesn't carry a floor, suite or room number, so a call from a phone on that option arrives with a street address alone. Its dynamic option takes each phone's location from the LAN switch or WiFi access point it's connected to, and that location can include the floor or suite.
Neither gap is visible to you when you dial. So when the call taker answers, say where you are, including the floor or suite.
U.S. Government Publishing Office (govinfo)
“Public safety answering point or PSAP. An answering point that has been designated to receive 911 calls and route them to emergency services personnel.”
Federal Communications Commission
“The latest NENA data indicate that 5,748 PSAPs operate in the United States.”
Federal Communications Commission
“data collected in our annual 911 fee report indicate that over 217 million calls are made to 911 in the United States each year”
Federal Communications Commission
“since then, 911 Authorities have issued more than 190 requests to begin Phase 1 service and one request for Phase 2 service. The requests cover parts or all of twenty-eight states and encompass more than 2,200 PSAPs.”
National Emergency Number Association (NENA)
“Public Safety Answering Point (PSAP): A set of call takers authorized by a governing body and operating under common management which receives 9-1-1 calls and asynchronous event notifications for a defined geographic area and processes those calls and events according to a specified operational policy.”
National Emergency Number Association (NENA)
“NENA i3 introduces the concept of an Emergency Services IP network (ESInet), which is designed as an IP-based inter-network (network of networks) that can be shared by all public safety agencies that may be involved in any emergency and a set of core services that process 9-1-1 calls on that network (NGCS).”
U.S. Government Publishing Office (govinfo)
“The requirements set forth in paragraphs (d) through (h)(2) and in paragraph (j) of this section shall be applicable only to the extent that the administrator of the applicable designated PSAP has requested the services required under those paragraphs and such PSAP is capable of receiving and using the requested data elements and has a mechanism for recovering the PSAP's costs associated with them.”
U.S. Government Publishing Office (govinfo)
“unless such system is pre-configured such that, when properly installed ... a user may directly initiate a call to 911 from any station equipped with dialing facilities, without dialing any additional digit, code, prefix, or post-fix, including any trunk-access code such as the digit 9”
King County, Washington
“King County is served by 11 Public Safety Answering Points (PSAPs), including 10 primary and 1 secondary center.”
North Carolina Department of Information Technology
“A secondary PSAP can receive voice and data from an enhanced 911 call transferred from a primary PSAP and complete the 911 process by dispatching law enforcement, ambulances, firefighters or other responders.”
National Conference of State Legislatures
“the average vacancy rate for public safety telecommunicators and emergency dispatchers nationwide was approximately 25% from 2019 to 2022”
Atlantech Online
“Calls to 911 are routed to a Public Safety Answering Point (PSAP). E911 identifies the location of the caller and routes the call to the appropriate local PSAP.”