Specifications

Chapter 7 Battery Reversal FXS/DPO
7-1
BATTERY REVERSAL FXS/DPO
CONFIGURATION
ABOUT THIS SECTION
This section describes how to configure the Access Bank I Battery Reversal Foreign Exchange Station
and Dial Pulse Origination (BRFXS/DPO) 12-channel voice card for connection to T1 public network
services and provides instructions for:
• Setting Transmit and Receive Levels
• Setting the FXS with battery reversal and DPO terminations
• Performing Voice Channel Monitoring and Testing
Battery Reversal FXS/DPO Voice Card
The BRFXS/DPO 12-channel voice card can be configured to operate either as a battery reversal FXS card
or Dial Pulse Origination (DPO) card. In the FXS with battery reversal mode, the BRFXS/DPO provides
twelve 2-wire CPE analog loop-start connections to the digital T1 line according to the same method used
by the FXS voice card, only with the addition of Tip/Ring battery reversal. The FXS interface reverses the
polarity of the battery feed towards the customer premise equipment (CPE) in response to the signaling
bits coming from the T1 line. Various PBX systems require battery reversal to signal the start of billing,
and in certain telephony environments it is needed to provide Line Side Answer Supervision (LSAS). One
important application for battery reversal occurs in International Call Back, which allows international
callers dialing the US to avoid more expensive inbound rates by taking advantage of cheaper US outbound
long distance rates. Dial Pulse Origination (DPO) termination is the functional complement to Dial Pulse
Termination (DPT) provided by the FXO/DPT voice card. Used in conjunction, the DPO and DPT cards
are used mainly for origination and termination of Direct Inward Dial (DID) circuits.
The BRFXS/DPO is a 7.8” by 13.16” daughter card designed to slide into the back of the Access Bank I
along rails that guide a 64-pin DIN connector to mate with a matched connector on the internal ABI
Controller. The card receives the T1 signaling, tip and ring pairs, control logic and power from the
Controller card through this connector. The back plate of the card has 12 channel status LEDs and one 4-
position DIP switch for selecting between battery reversal FXS loop-start and Dial Pulse Originating
(DPO) modes of operation. Furthermore, the back plate also contains 12 test switches that can be used to
“busy out” each channel individually. On the BRFXS/DPO card itself, each individual channel has a 6-
position DIP switch for setting transmit and receive line attenuation.