Crimestar's Mobile Digital Communicator (MDC) is designed to work over either a dedicated radio system operated by the law enforcement agency or via commercial carrier systems such as CDPD (Cellular Digital Packet Data - Made popular by AT&T) or GPRS (General Packet Radio Service).  These services provide the user with an IP connection to either the Internet or a VPN (Virtual Private Network).  These commercial services are typically provided by cellular phone carriers for a monthly fee.  Similar to Cellular telephone service, fees vary widely from carrier to carrier. Some companies offer discounted pricing to government entities or in conjunction with annual contracts etc.  While this type of commercial service is constantly expanding it is not available in all areas.  You should consult with your local carrier to determine if this type of service is available to you and the fees charged for the service.

By running the MDC controller on a machine that is connected to or exposed to either the Internet or your VPN (For security reasons a VPN is HIGHLY RECOMMENDED) with a fixed IP address, each MDC workstation can connect to and communicate with the controller via the TCP protocol.  Since (like cellular telephones) signals / IP connections can drop when an MDC unit moves into a "dead-spot", the  MDC software has error detection capabilities that will sense disconnects and automatically attempt to reconnect when a sufficient signal is again present.
 

The most typical format for these devices is as a PCMCIA card that plugs into the PCMCIA slot on your laptop computer.  Some allow for external antenna to increase signal strength.  However other more rugged truck mounted devices that connect to your computer via a USB or serial port are also available.
 

* Many states STRICTLY prohibit the use of commercial carrier network services or Internet connectivity on any machine or network that is also interfaced to your respective state law enforcement or motor vehicle computer system.  When these types of security restrictions are applicable a private dedicated RF modem system may be a better communications choice.

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