What Does Data Access Arrangement Mean?
Data access arrangement (DAA) is a computer modem with a built-in electronic system that interfaces with public switched telephone networks (PSTN). DAA is required for PSTN devices, including set-top boxes, fax machines, private branch exchanges (PBX) and alarm systems.
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DAA devices are isolated from high voltage phone lines, but system authorities require device registration. Preregistered DAA is built into most modems and devices.
DAA is also known as a telephone line interface circuit.
Techopedia Explains Data Access Arrangement
There are three international DAA standards:
- North America: Federal Communications Commission (FCC) Part 68, which parallels many Canadian and Mexican regulations
- Europe: European Telecommunications Standards Institute (ETSI) Common Technical Regulation (CTR) 21
- Japan: Japan Approvals Institute for Telecommunications Equipment (JATE)
A key DAA design factor is layout, which defines the area between line and modem components. Examples include:
- Optocoupler: Computer and phone line are connected without surge risk or damage
- Clare Based: Uses two high-voltage isolation capacitors to implement caller ID and ring detection with separate PSTN/pathways
- Capacitive-Coupled: Uses integral modem system components to directly interface with the digital signal processor (DSP)
- Simple: Includes incoming ring detector and hook switch relays and provides other application-specific functions
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