The voice card supports four channels of analog voice communications. It also provides the interface between the VSATPlus II system and a customer's telephone network.

Key features of the voice card include:

• Preassigned Multiple Access (PAMA) or Demand-assigned Multiple Access (DAMA) operation

• The Voice Card may be used in the PAMA and DAMA modes of operation. PAMA provides a full-period connection. In the optional DAMA mode, a pool of satellite channels is available for a channel to be allocated on demand. When a call is terminated, its channel is returned to the pool for reassignment.

• Dual-tone Multifrequency (DTMF) or dial-pulse signaling

• Encoding rates
  The voice card encodes and decodes audio using:

  • 64 kbps PCM in accordance with ITU-T G.711

  • 16, 24, or 32 kbps ADPCM in accordance with ITU-T G.726

  • 8 kbps CS-ACELP in accordance with ITU-T G.729A (voice encoding module (VEM) option)

• FXS/FXO interface signaling (option)
  The Voice Card supports FXS/FXO interface signaling with loop-start or ground-start reverse battery operation. The Voice Card includes an onboard, ringing voltage generator.
  The Voice Card uses optional FXS or FXO plug-in modules (PIMs) to provide subscriber-loop signaling:

• The FXO PIM provides an office-end interface to connect to a PBX; it also offers reverse battery supervision as a user-selectable option.

• The FXS PIM can be connected directly to a subscriber set; it also offers reverse battery supervision as a user-selectable option.

• With the addition of the FXS PIM, the Voice Card supports 16-kHz metering pulse operation for connection to pay phone terminal equipment.

• 2-Wire subscriber loop (FXS)
  A subscriber loop connects subscriber terminal equipment directly to the voice card within the VSATPlus II node. This subscriber terminal equipment includes rotary telephones, push-button telephones, fax machines, and modems.

• Onboard echo cancellers
  The voice card contains onboard echo cancellers with automatic tone disable. Echo cancellers are automatically disabled when a tone is received from a fax machine or modem.

• Loopback diagnostics
  Local and remote loopback diagnostic tests are available for testing the voice card's 4-wire E&M signaling. Both tests are individual channel loopbacks; each of the four channels can be individually tested. The local loopback checks the terrestrial access circuit and terrestrial interface. The remote loopback checks the entire card/channel data path, end-to-end, with the exception of the terrestrial interface in the remote card/channel.

• E1 Card compatibility
  The voice card is compatible and interoperable with the E1 Card for demand-assigned circuits.

• Channel-level enable/disable
  This function blocks the selected channels or all four channels on the voice card suitable for maintenance or testing purposes.

• Fax bypass (option)
  The fax-bypass capability is provided for channels.

• E & M Interface
  2- or 4-wire Type I-V E&M signaling with the addition of the E&M PIM, the voice card supports 2-wire or 4-wire voice frequency (VF) with Type I-V E&M signaling.

• ITU-compliant, fully compelled analog R2 signaling with several national variants

• Dial-up data (option)
  The voice card, when configured for dial-up data operation, emulates the physical and electrical interface of a Hayes modem. With this option, you can use the Hayes AT command set to connect terrestrial data terminal equipment (for example, personal computers or asynchronous devices) by dialing through any other dial-up data port in the network. A dial-up data option call is established using the same Demand-assigned Multiple Access (DAMA) call setup used for voice card DAMA calls.