Comdial DXP Plus Series, Руководство пользователя

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Direct Inward Dial (DID) T1 Trunk
DID is a protocol for inbound calls where the network sends the extension number during the beginning of the
call. The system supports the 0 through 7 inbound digits. The network does not translate the digits to a valid
extension—the system’s DID translation tables perform this action.
DS-0 (Digital Signal-Level Zero)
Digital Signal-Level Zero is a single 64Kbit channel inside a T1 span.
E & M T1 Trunk
E&M is a signalling protocol that supports both inbound and outbound digits. Inbound digits from the network are
already translated to a 3–digit or 4–digit valid extension. E & M is symmetrical from both ends and ignores the
subscriber/office classification of other trunks. Use this signalling protocol for interconnecting two DXP Plus
systems.
Extended Superframe Mode (ESF)
Extended Superframe Mode consists of 24 frames. The frame bit uses only 6 frames leaving 18 bits for other
purposes. These spare 18 bits provide 6 bits for CRC information and 12 bits for a facility data link. The facility
data link is for maintenance information (as defined by the ANSI T1.403 specification). Like the superframe
mode, the 64–Kbit user channels have 24 frames available for use.
Ground Start T1 Trunks
Ground start is a call signalling protocol that monitors only outbound digits and supports disconnect supervision.
Ground start protocol supports only the subscriber end of the communications link
FDL (Facility Data Link)
The Facility Data Link is a 4–Kbit communication link from the network to the DXPT1 board only when the
board is operating in the ESF mode. The system sends preemptive messages (for example, yellow alarm and
loopback), if needed, and sends error packets to the network once a second. The packets contain alarm history in
accordance with the ANSI T1.403 specification.
Fractional T1
Fractional T1 is a T1 span where the user uses less than 24 channels. The DXPT1 board allocates eight or 16
channels to a fractional T1 but does not reallocate unused channels in the eight, 16, or 24 mode to other resources.
A fractional T1 in ESF mode will nullify the CRC and other error checking capability since the network shares
channels.
Immediate Start Protocol State
Once a calling system seizes a called system, the calling system sends address digits to the called system without
requiring an acknowledgement. Inbound immediate start protocol does not support tone dial. Dial-pulse is
adequate however. Immediate start protocol is applicable to DID and E&M tie lines.
Inband Signalling
A signalling method where the system sends overhead signalling along with channel traffic.
ISDN (Integrated Services Digital Network) Primary Rate (also called PRI)
Currently not offered by the DXPT1 board.
Loopback Local
An operation method that loops the DXPT1 board’s transmit output and receive input paths. The loopback
terminates all traffic and halts call processing. While in this idle condition, the system continues to transmit the T1
transmit stream to the network but it will not answer incoming calls. If the remote T1 equipment is the clock
source (primary or secondary) for the DXOPT-SYN card, the remote equipment terminates the reference signal
because the network receive circuit is open in local loopback. You initiate local loopback by setting the
appropriate SW1 switches. The main purpose of local loopback is to verify the DXPT1 board’s ability to
synchronize properly. Loopback local operation is applicable to superframe adn extended superframe modes.
IMI89–193 Installing The DXPT1 Line Board
34 – Installing The DXPT1 Line Board