Four NG9-1-1 GIS Fields That Sound Similar, But Mean Very Different Things

May 22, 2026

One of the most common sources of confusion I see when helping agencies work through NG9-1-1 GIS data is the difference between Service URN, Service URI, Service Agency ID, and Discrepancy Agency ID.

Totally understandable. All four sound like they’re describing “the agency” or “the service,” but they actually answer four different operational questions.

The easiest way to explain it is this:

• Service URN answers: What kind of emergency service is being requested?
• Service URI answers: Where should the call be routed?
• Service Agency ID answers: Which agency does this service boundary represent?
• Discrepancy Agency ID answers: Who is responsible for fixing problems with the data?

Once those four questions are separated, the model starts to make much more sense.

The Service URN is about the type of service. It tells the NG9-1-1 system whether the routing request is for PSAP, law enforcement, fire, EMS, or another defined emergency service. It does not identify the agency. It identifies the category of service being requested.

The Service URI is about the routing destination. If the Service URN says, “I need fire service for this location,” the Service URI is the destination the system should use to route that request. These values are typically coordinated with the NGCS provider, ESInet provider, state 9-1-1 office, or other routing authority.

The Service Agency ID is about the agency represented by the service boundary. A law enforcement boundary may represent a city police department, a county sheriff’s office, a tribal police department, or another responding agency. A fire boundary may represent a municipal fire department, a fire district, or another fire response provider.

This is where many users get tripped up. The Service URN may say “law enforcement,” but the Service Agency ID says, “this specific agency provides law enforcement service for this area.”

The Discrepancy Agency ID is different again. It identifies the agency responsible for receiving and resolving discrepancy reports when data problems are found.

That may be the same organization as the service provider, but it does not have to be.

For example, a fire service boundary may represent a local fire department, while the GIS data corrections are handled by a countywide or regional data steward. In that case, the Service Agency ID and Discrepancy Agency ID should not be forced to match.

A simple way to remember the difference is:

Service Agency ID = who the boundary represents.

Discrepancy Agency ID = who fixes the data.

This distinction becomes especially important in countywide, regional, tribal, military, or statewide NG9-1-1 environments.

Imagine a location on tribal land within a countywide NG9-1-1 system. The addressing authority may be the tribe. Law enforcement may be tribal police. Fire response may come from a neighboring fire district. GIS discrepancy reports may be routed to a countywide data steward.

None of those are contradictions. They are separate responsibilities.

That is why these fields should not be collapsed into one concept just because the same agency sometimes performs more than one role.

In the simplest terms:

Service URN tells the system what type of service is needed. Service URI tells the system where to route the call. Service Agency ID tells the system which agency the boundary represents. Discrepancy Agency ID tells the system who is responsible for correcting the data.

NG9-1-1 GIS is not just about drawing accurate boundaries. It is about clearly defining service responsibility, routing behavior, and data stewardship so the system knows what to do when a call is placed — and when a data problem is found.