Quick Guide
Emergency
Master Street Address Guide (MSAG)
What is a Master Street Address Guide (MSAG)?
A Master Street Address Guide (MSAG) is a directory that maps out every valid street address within a geographical area. These allow for proper 911 call routing to any address range.
State and municipal authorities are responsible for updating the MSAG Directory and making it available for use. For any specific MSAG questions, contact your particular state or municipal authority.
How is Bandwidth involved with MSAGs?
Bandwidth utilizes MSAG when it comes to our 911 access services. We start with your submitted civic/postal addresses, which we then geo-code to assign an X/Y coordinate for each record, confirming successful validation. We then store the geo-coded address in the MSAG-compliant format for the jurisdiction in question.
Each telephone number’s address is then immediately available to respond to PSAP queries. Bandwidth subscribes to the most current geo-code databases available, in addition to working with all of the 911 authorities to obtain MSAG and GIS files. Our dedicated support team in turn ensures timely updates to the validation engine. With us, the entire process takes minutes instead of days or potentially weeks from competing providers.
MSAG terms to know
| Term | Definition |
| MSAG (Master Street Address Guide) | Master Street Address Guide (or “MSAG”) is a database of street names and house number ranges within their associated postal communities that define Emergency Service Zones (ESZs) and their associated Emergency Service Numbers (ESNs) to enable proper routing of 911 calls. |
| MSAG Address | An MSAG address is recognized by Public Safety for the dispatch of emergency responders. It is an absolute and unique address because it fits a formatting in which variants for directions, street spelling, street suffixes, and community names are not allowed. |
| Emergency Service Zone (ESZ) | An Emergency Service Zone (ESZ) is a designated area where emergency responders receive prioritized communication during crises. They ensure reliable connectivity for first responders when networks are strained or failing. |
| Emergency Service Number (ESN) | A System Identification Number (SIN), formerly an Emergency Service Number (ESN), is a unique technical identifier assigned to mobile devices by carriers. It authenticates devices and allows them to connect to the wireless network. |
| MSAG Coordinator / Administrator | An MSAG Coordinator/Administrator is responsible for maintaining and updating the MSAGso that Public Safety Answering Point (PSAP) dispatchers can accurately locate and dispatch help to callers. |
| MSAG Delta | MSAG Delta refers to a file containing changes to the Master Street Address Guide (MSAG). It’s a concise update package sent to Public Safety Answering Points (PSAPs) to efficiently refresh their MSAG data without transmitting the entire database. |
| MSAG Baseline | The MSAG Baseline is the full, initial Master Street Address Guide dataset provided to a 911 center. It serves as the starting point against which all future MSAG updates (Delta files) are applied to keep address data accurate. |
| MSAG Error / Discrepancy | An MSAG Error/Discrepancy represents inaccurate or conflicting information within the Master Street Address Guide (MSAG), such as incorrect addresses, misaligned geographic data, or inconsistencies between the MSAG and authoritative sources. These can lead to inaccurate 911 location information, potentially delaying emergency response and endangering lives. |
| Civic Address Format | Civic Address Format refers to the standardized structure and components of a street address, typically consisting of a street number, street name, unit/apartment number (if applicable), city, state, and zip code. This standardized format is essential for accurate geocoding and location information in emergency calling systems. |
| MSAG Operator | An MSAG Operator is the organization responsible for creating, updating, and maintaining the Master Street Address Guide (MSAG). They manage official address data, correct errors, and provide updates to ensure accurate 911 call routing and location information. |
| MSAG Consumer | MSAG Consumers are organizations that use Master Street Address Guide (MSAG) data to validate addresses and correctly route 911 calls. They rely on MSAG accuracy to ensure callers are matched to the right emergency responders. Examples include: Public Safety Answering Points (PSAPs), 911 dispatch centres, NG911 call-routing systems, Address‑validation systems used by emergency service providers |
| MSAG Source | An MSAG Source is basically where the official address information comes from. Think of it as the “official record” of street addresses – like the county government or the postal service. This information is then used to create the MSAG. Sources include local government agencies, state mapping agencies, US Postal Services (USPS), and Cooperative Geographic Authorities (CGAs). |
MSAG FAQ
If an address isn’t recognized or validated in the MSAG system, here’s what typically happens:
- The 911 call may not route to the correct Public Safety Answering Point (PSAP).
- Dispatchers may receive incomplete or incorrect location info.
- Emergency responders might be delayed because the address must be verified manually.
- The issue is usually sent to the local MSAG Coordinator/Administrator for correction, which may require updating street names, address ranges, or GIS data.
Depending on how your state or city handles 911 data you have a few options:
- Your local 911 authority or PSAP: Many counties and cities have a 911 addressing office or GIS/Addressing department that manages MSAG and can answer address‑related questions.
- Your state’s 911 board or emergency communications office: Most states have a statewide 911 authority, commission, or emergency communications division that oversees MSAG standards, addressing policies, and updates.
- Your local city or county GIS/Addressing department: These teams maintain official address records that feed into the MSAG and can resolve discrepancies or new‑address issues.
- Your local MSAG Coordinator/Administrator: Some jurisdictions publicly list their MSAG coordinator for address corrections, MSAG validation questions, and error resolution.
Bandwidth updates its geo‑code and MSAG databases on a daily basis. These updates incorporate the latest MSAG Baseline and Delta files received from the MSAG Operator, along with new or corrected address data from local authorities.
What this means for our customers:
- Address validation reflects the most recent MSAG updates.
- New addresses, corrections, and changes from cities/counties are added as soon as they are published by the authoritative source.
- Any MSAG discrepancies detected are processed as updates become available.
Related terms
The information provided in this glossary definition does not, and is not intended to, constitute legal advice, nor does it necessarily represent Bandwidth's products or business practices. This page is for general informational purposes only.Related posts
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