AT&T MERLIN LEGEND Key System Planning page 70

Lines
See "Signaling Mode" in this chapter.
Frame Format
3-16
Line options
Planning Form Instructions
On Key System Form 2c, System Numbering — Line Jacks, in the "Jack
Type" column:
1 .
Find all lines listed as "PRI"
Write the kinds of service connected to each channel in the "Line Type"
column.
Note: You cannot use the 24th channel for services.
Write "unequipped" in the "Line Type" column for any channel not used
at this time.
2 .
Find all lines listed as "T1—Tie" that do not show "unequipped" in the "Line
Type" column, and write the kind of service connected to each channel
in the "Line Type" column.
Note: If the signaling type is common - channel, you cannot use the
24th channel, and you must program the module for tie-line emulation.
On page 1 of Key System Form 3c, Outside Lines — DS1 Facility (100D
Module), for each 100D Module in the system.
3 .
Write the number of the control unit slot that contains the module inthe
"Slot No." blank. (Refer to the "Control Unit Diagram" on Form 1.)
If more than one 100D Module is used, complete the first column,
"Module 1", to show the options assigned to the 100D Module in the
lowest number control unit slot. Use the second column for the second
lowest number slot, and the last column for the highest number slot.
4 . Show the service connected to each 100D MOdule under the "Type of
Service" heading.
Check "T1`" (the factory-setting) if the module is used for emulated lines
and/or services such as Megacom 800 with DNIS.
Check "ISDN—PRI" if the module is used exclusively for services such
as Accunet Switched Digital Service.
To identify the DS0 channels, the DS1 signal is segmented into blocks of 193
bits, called frames. A frame consists of 24 eight-bit words (one for each
channel) plus a framing bit at the beginning of each frame: 24 words x 8 bits =
192 bits. Thus, a framing bit appears in every 193rd bit position of the
1.544-Mbps DS1 signal.
Frames repeat at a rate of 8000 per second, with each frame repeating DS0
channels 1 through 24 sequentially.