Nortel DMS-100 Series Maintenance Manual page 44

1-28 Maintenance overview
After the TPT software receives CM primitives, the TPT software sends
messages to other call processing software areas. Important messages
include the following:
The DDL facility software module
The TPT messages that the DDL facility receives determine the messages
that the DDL facility sends to the RCS. The DDL messages can include
assignment of DS-1 channels to subscriber loops, and activation of the PCM
loop test.
297-8231-550 Standard 09.01 August 1998
requests for channel and loop tests
requests for the system to generate a forward disconnect pattern on a
channel to an RCS. The forward disconnect pattern causes a line card
with an associated keyset to force the keyset to drop the call-holding
bridge. The keyset drops the call-holding bridge on abandoned
telephone calls.
requests for ANI and coin functions
Note: The system performs forward disconnect processing for
single-circuit line cards that connect to keysets. The forward disconnect
signaling pattern causes the line card to short the loop tip and ring
together. The process causes key telephone sets to drop the call-holding
bridge on abandoned calls.
messages to the DDL facility that request the DDL facility to assign or
deassign a channel to a subscriber loop. These messages can request a
PCM loop test as part of the assign message (Mode II).
messages to the DDL facility that request the DDL facility to make
channels associated with equipped, active loops available. The DDL
facility maintains an inventory of available DS-1 channels.
messages to the A/B-bit facility. The messages request the A/B-bit
facility to inspect equipped, active subscriber loops for on-hook and
off-hook states. The facility also performs the following functions:
— collect digits
— send out ANI and coin requests to the RCS
— scan the responses to ANI and coin requests
— send or cancel the forward disconnect signaling pattern on the correct
channel to the specified subscriber loop
messages to the UP ringing task that request the UP ringing task to start
or stop ringing on a subscriber loop
Note: Single-circuit cards in Mode II have DS-1 channel assignments
that are fixed.