CA VoIP E911 GIS Shape File Recommendations
Background: County Coordinators have been asked by the State 9-1-1 Office to work with the
Voice Positioning Centers (VPCs) to ensure accurate call routing of VoIP calls. VoIP calls are
geocoded (translated from an address to a Lat/Long) and then routed using electronic maps
known as shape files. These maps contain PSAP ESN jurisdiction information. Key to
coordination has been for the County Coordinators to use any existing maps within the county to
The following information is intended for the County Coordinators to use in discussions with the
GIS entities. For County Coordinators that do not have access to GIS resources, they will need
to manually verify maps from each VPC. The following recommendations are provided for the
purposes of incorporating PSAP and/or ESN boundaries into the VPC’s GIS, which will be
ultimately used for E9-1-1, call routing. This information is comprised of input from the VPCs and
the State 9-1-1 Office.
The italicized, red text provides the rationale for each GIS data requirement.
County Wide updates:
Updates are on a countywide basis with all updates to each PSAP/ESN within the
county included in the file. This will assist the GIS Analyst in incorporating all changes
for that particular county as opposed to receiving separate updates per PSAP/ESN.
Also, since the GIS data will be topologically sound, this will greatly assist the GIS
Analyst in minimizing the amount of work it takes to resolve spatial discrepancies
between polygons if they were supplied on a PSAP/ESN level.
Changes to all PSAPs/ESNs included in the file must first be validated by the County
Coordinator prior to incorporating into the VPC GIS. This will minimize any
discrepancies or conflicts between PSAPs.
Unless specifically stated otherwise by the County Coordinator, for those PSAP/ESN
boundaries that extend beyond the county boundary, that portion of the PSAP/ESN
polygon will not be incor