AT&T MERLIN LEGEND Data Manual page 28

Data Communications with This System
Outside Lines/Trunks
See System Reference for detailed
information and programming
requirements for tie trunks.
See System Reference for detailed
information and programming
requirements for DID trunks.
Figure 1-4 shows the types of outside lines/trunks that can be used to make and
receive data calls to outside data stations.
1.
GS (ground-start) Iines/trunks are used to place and receive data calls
from an outside analog data station and also provide improved signaling and
a dependable disconnect (for secure toll restriction).
LS (loop-start) Iines/trunks are the standard for home and small
businesses. They are less expensive in some areas but
they do not protect against "glare." Glare occurs when an outside call is
made at the same time as another call is arriving.
they cannot provide dependable disconnect for toll restriction
The following outside GS/LS lines/trunks can be used for data:
basic lines/trunks
WATS (wide area telecommunications service)
800 service (in-WATS)
foreign exchange (FX)
GS/LS Iines/trunks connect to GS/LS jacks on the system.
2. Tie Trunks provide private communications between two systems. Tie trunks
"tie" the two systems together, providing access to all telephones or data
stations on each system.
Tie trunks are usually used for data communication with analog stations
connected to a system at a different location, such as different floors of a
building, different buildings, and different cities or states.
Tie trunks connect to the system on a 400EM module.
3.
DID (Direct Inward Dial) Trunks allow incoming calls to reach specific
individuals or facilities in the system without the help of a system operator.
DID trunks are available only in the Hybrid/PBX mode.
DID trunks are used to receive calls from outside analog data stations.
Outgoing calls cannot be placed on DID trunks.
DID trunks connect to the system on an 800 DID module.
4.
DS1 facility carries digital signals in the Digital Signal 1 (DS1) format.
The DS1 format passes digital data at 1.5444 Mbps by multiplexing twenty-
four 64-kbps Digital Signal 0 (DS0) signals and an 8-kbps framing signal.
Even though there is only one physical jack, the 100D module supports up to
twenty-four logical endpoints or ports (one for each channel) for voice and
data calls.
Each DS0 channel in the DS1 signal corresponds to a line/trunk or logical ID.
Data Communications Components
1-11