E911 Network Communications
 

The E911 interface communicates with other Crimestar CAD workstations via UDP multipoint broadcasts; with the Crimestar database and via a serial communications port.  In order to communicate with the other CAD workstations it is critical that machine running the E911 interface be on the same network segment or class “C” address range as the CAD workstations.   Additionally, the E911 interface uses the Crimestar INI file to locate the Crimestar database.  For the Professional Edition, the software uses the DATAFILES= setting in the [PATH] section of the INI file to locate the shared database files.  In the Enterprise Edition the SQL_NAME_IP= setting in the [CONFIGURATION] section is used to find the computer that is hosting the Microsoft SQL Server Crimestar database.  If a router, switch or firewall is in place on the network it should allow for the passage of TCP/UDP traffic on port 333.  This is the port that the E911 Interface controller uses to notify a CAD workstation of E911 ALI/ANI data.

Since the 911 ALI data ends up at a CAD workstation many people mistakenly think that the E911 interface program send the ALI data to the CAD workstations, or that the E911 interface application needs to be run at the CAD workstation but this is not the case.  The following diagram shows the data flow process used in the E911 interface.

The above diagrams illustrates the data flow between the E911 PSAP Telco equipment and the CAD Workstations.  The ANI/ALI data is received from the Telco Equipment by the Crimestar E911 interface application.  The Crimestar E911 interface application typically runs on the server or on a separate computer from CAD workstations.  The inbound ASCII text (ANI/ALI) data is parsed into discreet data elements including the PSAP workstation ID for the operator who is answering the call.  The ANI/ALI data is then placed into the E911 data table of the Crimestar database for the specific PSAP workstation ID answering the call.  Then the E911 interface application sends a UDP broadcast message on port 333 to the CAD workstations notifying the workstation that E911 data has been received and that the ANI/ALI data is available for recall.  The Operator at the CAD workstation can then retrieve that data from the Crimestar database as desired.