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ISI Internet Serial Interface

The Hark ISI is a hardware device that encapsulates serial data into TCP/IP for transmission over the Internet. It can also be configured to convert incoming TAP or TNPP messages from the serial port and send them over the Internet to paging providers in email (SMTP), Simple Network Paging Protocol (SNPP), or Wireless Communications Transfer Protocol (WCTP) format. It can emulate a modem and intercept the dialed number using it to route TAP messages to SNPP providers or pass them through to a modem if the provider does not support SNPP. The ISI-LX with the optional external modem can connect to a secondary dial-up ISP when a failure on the ethernet port is detected.

ISI diagram

This device is the perfect companion for the Hark Gateway products. An ISI can be located at a remote location for receiving TAP, TNPP, or Billing traffic using a local ISP eliminating long distance or leased line phone charges.


  • Hardware Based
  • Uses Embedded Linux as the Multitasking OS
  • Secure access for Configuration and Maintenance
  • Converts Serial TAP or TNPP message to SMTP, SNPP, or WCTP
  • Converts Serial Data to TCP/IP and TCP/IP back to Serial (passthrough mode)
  • Connects to Internet using Ethernet Network
  • Connects to Internet using PPP over modem
  • Dial Backup to another ISP or Modem
  • Can be Configured to use 1 to 4 Serial Ports
  • No moving parts such as hard drives or fans to wear out
  • Version 2.22 and higher support sending WCTP/SSL for encrypted messaging

System requirements

  • Internet connection
  • DB-9 serial cables