ISO 21792:2019

Overview

ISO 21792:2019 - Ships and marine technology: Guidelines for onboard telephone equipment - gives practical recommendations for the design, installation, performance testing and maintenance of shipboard telephone systems. The standard covers automatic telephones, common battery telephones (DC 24 V), battery-less telephones and sound‑powered telephones, and specifies shop tests, onsite tests, and maintenance tests to verify functionality and reliability. It does not apply to digital, LAN/VoIP or wireless telephones (these were excluded while under development).

Key Topics

• Scope and terminology
  • Definitions for telephone types (automatic, common battery, battery-less, sound‑powered) and equipment such as automatic telephone exchangers.
• Quality of communication
  • Recommendations to ensure intelligible voice transmission and connectivity across shipboard telephones.
  • Measures to prevent howling (audio feedback) and to suppress ambient and narrowband noise.
• Data and signal requirements
  • Signal condition, input/output considerations and connection guidance for automatic and analog telephones.
• Installation requirements
  • Environmental considerations (temperature, vibration, swinging motion), dust/water protection, explosion protection and cabling best practices for shipboard environments.
• Performance testing
  • Shop tests for factory verification and onsite tests for installation acceptance (automatic and non-powered telephone types).
• Maintenance
  • Routine and periodic maintenance procedures, corrosion mitigation, periodic maintenance programmes and recommended replacement periods.

Applications

ISO 21792:2019 is directly applicable to the selection, installation and upkeep of onboard telephone equipment in merchant vessels, offshore units and other marine platforms. Typical uses include:

• Designing ship communication systems and specifying shipboard telephones for newbuilds and refits.
• Preparing factory acceptance and onboard commissioning test plans (shop and onsite tests).
• Developing maintenance schedules and spare/replacement policies for telephony hardware.
• Guiding manufacturers on performance and environmental requirements for maritime telephone products.

Target users: shipbuilders, marine equipment manufacturers, ship owners/operators, classification societies, marine engineers and shipboard technicians.

Related standards and references

• Prepared by ISO/TC 8 (Ships and marine technology), Subcommittee SC 6 (Navigation and ship operations).
• For terminologies and electrotechnical definitions consult IEC Electropedia and the ISO Online Browsing Platform.
• Note: ISO 21792:2019 complements other international shipboard communications and electrical installation guidance; consult relevant IMO, IEC and national maritime regulations when applying this standard.

Keywords: ISO 21792:2019, onboard telephone equipment, shipboard telephones, automatic telephones, sound-powered telephones, common battery telephone, battery-less telephone, performance tests, maritime communication systems.