2/4-Wire Special Services (SS 2/4) Plug-in Card
The Tellabs 1000 MSAP 2/4-Wire Special Services plug-in card (SS 2/4) offers a multitude of 2-wire and 4-wire nonlocally switched and nonswitched intra-LATA voice and data services. These include Foreign Exchange (FXS) and long-distance lines, WATS, 800, Centrex, secretarial and off-premises extension lines as well as two-point and multipoint private line services. The SS 2/4 card supports two circuits. Each circuit on the SS 2/4 card can be used as a 2-wire or 4-wire circuit. The card supports FXS, Foreign Exchange Office (FXO), Direct Inward Dialing (DID), Equalized Transmission Only (ETO) Private Branch eXchange (PBX) and Private Line, Automatic Ringdown (PLAR) functionality.

Features and Benefits

  • Two circuits per card, each able to support 2- or 4-wire operation
  • 2- or 4-wire FXO
  • 2- and 4-wire FXS
  • 2- and 4-wire ETO
  • 2- and 4-wire PLAR
  • 2- and 4-wire DID
  • Equalization
  • Gain transfer
  • Normal or reverse simplex
  • Loop start or ground start

Included Highlights

More Choices

Also available in the 4-wire mode is selectable normal or reversed simplex signaling. In both 2-wire and 4-wire interfaces,provisionable wide-range gain/attenuation settings are provided. For ETO mode, both sourcing or sinking sealing current options are available when sealing current is required. The SS 2/4 card is not software upgradeable.

Signaling Modes

For all signaling modes, the Tellabs 1000 MSAP SS 2/4 plug-in card supports full equalization for 2-wire interfaces and built-in precision balancing with each equalization setting for echo cancellation over any loop. For 4-wire interfaces, post-equalization (transmit direction only) is provided. These equalization settings are available via provisionable selections for different cable configurations. Passive mismatch equalization is also available in the 4-wire mode, via selectable 150 ohm/600 ohm settings, for both transmit and receive directions.

POTS services

Connecting POTS telephones to a computer telephony system via T-1 links requires a channel bank configured with FX-type connections. Generating a call from the POTS set to the computer telephony system requires a configured FXO connection. Generating a call from the computer telephony system to the POTS set requires a configured FXS connection.

FXO and FXS services

FXO or FXS service can be ordered from telcom service providers outside the subscriber’s exchange area. With this service, a user can pick up a phone in one city and receive a dial tone and a local number from a “foreign” city. FX trunks provide the connection. Analog or T-1 links transport the signal.


  • Weight: 0.5 lb (0.23 kg)
  • Depth: 10.5 in (26.67 cm)
  • Width: 0.563 in (1.429 cm)
  • Height: 5.125 in (13.018 cm)
  • External interface inputs/outputs are available via backplane wire-wrap posts of the slot where the ETI card is located.
Power Consumption
  • Relative humidity: 5%-95% noncondensing
  • Operating temperature: -40 F to +149 F (-40 C to +65 C)
  • Meets GR-1244-CORE filter requirements
  • Current Sink Interface - End-to-end signaling delay (normal and reverse battery): < 50 ms - Wink distortion for any off wink > 50 ms: ±15 ms - On-hook interval distortion for intervals > 50 ms: ±25 ms - Maximum DC supervisory range: <= 1600 ohms - Ring Detection: < 100 ms - AC Ringing load (20 Hz): > 2.3 k ohms but < 4.0 k ohms - Nominal DC input resistance: Selectable — 500 ohms, 250 ohms - Ring Ground resistance: 600 ohms
  • Signaling Types (2-wire and 4-wire) - D4 FXS, FXO, loop start and ground start - D4 DP0, D4 DPT, TR-8 DPT, TR-8 FXS - D4 PLAR, D4 FXS/PLAR, D4 PLAR D4, ETO
LED Indicators
  • Green, BUSY - Either channel is in any state other than Idle or Invalid Signaling, and no hardware failure is detected on the card
  • Red, Fail - A hardware failure is detected on the card, or the card is unable to communicate with the CPU
  • Craft User Interface (CUI)
  • Tellabs Panorama Element Management System (EMS)
Software Support
  • Minimum base software FP15 and higher
  • Supported in Tellabs 1000 CBA
Current Feed Interface
  • Open circuit voltage: < -43V
  • Ring trip delay: < 150 ms
  • Loop current: Typically 25 to 30 mA
  • On-hook detection threshold: > 10 k ohms
  • Off-hook detection threshold: < 2 k ohms
  • Maximum DC supervisory range - Includes 1600 ohms maximum cable resistance plus 430 ohms for station:
  • Wink distortion for any off wink > 50 ms: ±15 ms
  • End-to-end signaling delay (normal and reverse battery): < 50 ms
  • Line impedance, 2-wire Terminal mode (COT and RST): selectable 600 ohms + 2.16 F or 900 ohms + 2.16 F, 2-wire Cable mode (RST and COT): 900 ohms + 2.16 F, 4-wire Terminal mode: 600 ohms, 4-wire Cable mode: Selectable 150 ohms or 600 ohms for unloaded cable; fixed 1200 ohms for loaded cable
  • Receive gain adjustment (from DLC), 2-wire Terminal mode: -10.0 dB to 0.0 dB, 2-wire Cable mode: +6.0 dB to –9.0 dB, 4-wire Terminal mode: -16.0 dB to +8.5 dB, 4-wire Cable mode: -9.0 dB to +6.0 dB
  • Transmit gain adjustment (toward DLC), 2-wire Terminal mode: -5.0 dB to +4.5 dB, 2-wire Cable mode: 0.0 dB to +9.0 dB, 4-wire Terminal mode: -7.0 dB to +17.5 dB, – 4-wire Cable mode: -6.0 dB to +9.0 dB
Return Loss
  • Idle channel noise - < 20 dBrnC
  • Longitudinal balance - 200 Hz to 2 kHz, > 58 dB and 3 kHz, > 53 dB
  • At COT with RT in Cable mode - ERL: 10 dB min and SRL: 5 dB min
  • At RT with COT in Cable mode - ERL: 15 dB min and SRL: 9 dB min
  • At COT with RT in Terminal mode - ERL: 22 dB min and SRL: 14 dB min
  • At RT with COT in Terminal mode - ERL: 19 dB min and SRL: 11 dB min
  • Mixed gauges are allowed with any combination. All loops longer than 18,000 ft must use H-88 loading. Loaded cable: Only H-88 loading is supported. Gauges of 19, 22, 24, and 26 are supported, including any gauge combinations. Maximum customer end section length including bridge taps is 9000 ft for 2-wire and 15,000 ft for 4-wire (from last load coil). No bridge taps are allowed in (or between) the loaded sections.
  • Supported cable facilities - Nonloaded cable: 19, 22, 24 and 26 gauges are supported up to 18,000 ft, including bridge taps. Maximum bridge tap length is limited to 6000 ft for 2-wire and 12,000 ft for 4-wire.
  • Supported cable configurations - 2-wire and 4-wire Terminal interface: up to 3,000 feet of intraoffice cable, but = 1.5 dB 1 kHz loss – 2-wire and 4-wire cable interface: maximum cable length is limited to 10 dB 1 kHz loss or 1600 ohms DC cable resistance.
  • Meets GR-57-CORE requirements for attenuation distortion for supported cable configurations – 2-wire cable mode: active equalization provided in both directions of transmission – 4-wire cable mode: active postequalization in transmit direction. Passive equalization using 150 ohm mismatch also provided.
Product Specifications Sheet

2/4-Wire Special Services (SS 2/4) Plug-in Card
Product Specifications
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