Specifications

Line and Station Boards and Special Components
GCA39-825 Rev 2, Issue 4/02 Page 6 Printed in the USA
Digital T-1 and ISDN Primary Rate Interface Boards
Part Number: FXT1-24 (24-Channel Digital T-1 Line Board)
Part Number: FXT1-PRI (23- Channel Digital T-1 with Primary Rate Interface Daughter Board
and Firmware Upgrade)
• 1 synchronization card is required for T-1 operation and for PRI applications. Only 1 sync
card is needed. (Refer to Auxiliary Equipment in this section for more information.)
• A T-1 Interface allows up to 24 channels of voice transmission over a single 4-wire cable.
• The T-1 supports loop start lines, ground start lines, tie lines, and DID lines. You must
determine what portion of the 24 channel T-1 should be dedicated for each particular type of
line needed in your configuration. The default line in VMMI for all T-1 channels is Loop
Start.
• A customer service unit (CSU) is built into the T-1 option board to terminate the T-1
channels. This eliminates the need to install a CSU external to the system. The CSU protects
the board against voltage surges, provides transmission drive up to 6,000 feet for a direct host
to remote connection, and performs diagnostic tests for the network.
• If necessary, an external CSU/DSU can be added to the system to break out channels for data.
• Since each board slot in the system has 32 time slots, each T-1 board only needs 1 board slot
for full 24 channel operation.
• ISDN-PRI provides a way for subscriber to get digital service from the Telephone Company
over 2 special pair of wires.
• The PRI card supports 23 bearer channels and 1 data channel.
• With the “D” channel, ISDN provides enhanced signaling capabilities, which can be
beneficial in data-intensive environments. (Currently only voice and modem calls are
supported.)
• PRI circuits allow for dynamic allocation of trunks. So, if 10 channels have been allocated to
DID and an 11
th
caller calls in, instead of a busy, the 11
th
caller can be floated to another
available trunk.
• Feature support includes: Calling number identification services, PRI interactions with lines,
line groups and system features, and direct dialing in.
• A PRI-board can be purchased from Comdial in a pre-built standard package, or a T-1 board
can be upgraded to a PRI-board. All that is required is a firmware upgrade and Interface
board add-on to the standard T-1 option card.