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All-Rate DSU/CSU


ADTRAN Products
Adtran DSU III AR standalone
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The ADTRAN® DSU III AR™ is a technologically advanced, high performance data service unit/channel service unit (DSU/CSU). This unit provides a reliable interface between the digital data service (DDS) or 4-wire Switched 56 (SW56) network and the customer’s data terminal equipment (DTE). The unit is an all-rate DSU/CSU supporting synchronous and asynchronous data rates on the primary channel and asynchronous data rates on the secondary channel. The synchronous primary channel rates supported are 2.4, 4.8, 9.6, 19.2, 38.4, 56, and 64 kbps. Asynchronous data rates supported are 2.4, 4.8, 9.6, 19.2, 38.4 and 57.6 kbps. Secondary channel data rates of 75, 150, 300, 600, 1200, and 2400 bps are offered depending upon the primary channel rate.

The DTE interface can be selected as either EIA-232 or V.35 for all data rates. The secondary channel interface is EIA-232 and is accessed through a separate connector.

Additional features of the DSU III AR include a DTE-to-service rate matching feature for both dedicated and switched modes, as well as various anti-streaming time-out values, to disable streaming terminals on a multi-point circuit. Private networks and modem tail circuits are accommodated through clocking/timing options.

In the 4-wire SW56 mode, dialing options include manual dialing, redialing, and dialing of stored numbers. Dialing over the DTE interface is supported by use of an AT command set or the V.25 bis in-band dialing protocol.

The unit responds to standard loopback commands from the telephone company central office. In addition, the user has several built-in test capabilities. These include V.54 remote loopback, 2047 and 511 BERT test patterns, and four DDS stress patterns (results of which are displayed on a two-line by 16-character LCD display and seven LEDs). The standalone unit’s front panel keypad supports setup, selection of test modes, local and remote configuration, manual dialing, or automatic dialing from stored numbers.

The rackmount unit can be configured through the Smart 16/16e shelf controller card, from a local/remote VT100 terminal or from an ADTRAN DATAMATE. The DSU III AR can also be configured using AT or V.25 bis commands. A DC version of the standalone unit is also available. The DSU III AR DC supports all the functionality of the DSU III AR, except secondary channel.


  • Support for rates from 2.4 to 64 kbps including 19.2 and 38.4 kbps
  • Standalone or Smart 16/16e shelf rackmount versions
  • Compatible with DDS secondary channel services; provides asynchronous secondary channel rates of 75 bps to 2.4 kbps
  • Local and remote configuration (AT, front panel, V.25 bis)
  • Synchronous or asynchronous (including 57.6 kbps) primary channel modes of operation
  • Both EIA-232 and V.35 primary channel DTE interfaces
  • DTE-to-service rate matching feature allows slower DTE devices to communicate over higher speed service offerings
  • Manual, DTR Dial, AT commands, V.25 bis, or stored number dialing capabilities
  • Auto answer of incoming calls
  • Industry-leading five-year North American warranty


Operating Modes
  • Dedicated DDS (point-to-point, multi-point)
  • Switched 56 (4-Wire)
Network Data Rates
  • Dedicated mode service rates: 2.4, 4.8, 9.6, 19.2, 38.4, 56 and 64 kbps
  • Switched mode service rate: 56 kbps
DTE Rates
  • DTE-to-loop rate matching in both dedicated and switched modes
  • Synchronous rates
    2.4, 4.8, 9.6, 19.2, 38.4, 56, and 64 kbps
  • Asynchronous rates
    2.4, 4.8, 9.6, 19.2, 38.4, and 57.6 kbps
DTE Interface
  • Both EIA-232 and V.35 electrical and physical primary channel DTE interfaces
  • EIA-232 secondary channel interface
Switched Mode Dialing Options
  • Stored number
  • Front panel keypad (standalone only)
  • DTR dialing of stored number
  • In-band AT commands
  • V.25 bis in-band dialing
Data Buffering
  • Internal slack buffer
  • Normal DDS or private network tributary (slaved to network receive clock)
  • Private network master (internal)
  • Normal DDS with tail circuit
  • Private network master (slaved to external clock)
  • CSU and DSU loopbacks
  • Local DTE and loop
  • Remote V.54
Test patterns
  • 2047, 511, DDS stress patterns 1-4
Receiver Sensitivity
  • –45 dB at all rates
Agency Approvals
  • FCC Part 15, Class A
  • FCC Part 68
  • Industry Canada CS03
  • UL and CUL
  • 0° to 50°C (32° to 122°F)
  • –20° to 70°C (–4° to 158°F)
Relative Humidity
  • Up to 95%, non-condensing
  • Standalone: 2.25" H, 8.75" W, 10.25" D
  • Rackmount: 1" H, 6.75" W, 10.50" D
  • Standalone (DC): 2.4" H, 8" W, 10.4" D
  • 3 lbs
  • 1.5 lbs
AC Standalone
  • 115 VAC, 60 Hz, 8 watts
DC Standalone
  • 20-60 VDC, 8 watts


Download the ADTRAN DSU III AR Datasheet (PDF).


ADTRAN Products
Adtran DSU III AR standalone
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Adtran DSU III AR DC standalone
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Adtran 19” Dual ESP Shelf (for DSU III AR DC)
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