Nortel DMS-100 Series Maintenance Manual page 48

1-32 Maintenance overview
Call processing sequence of events—terminating end
The following sequence of events occurs during call processing at the
terminating end of a call:
1 The TPT sends a message to the UP ringing task to start ringing the
2 The UP ringing task schedules ringing. The UP ringing task sends a
3 When the A/B-bit facility detects an answer, the A/B-bit facility sends a
4 The UP ringing task directs the A/B-bit facility to stop ringing on the
5 The TPT sends a message to the A/B-bit facility. The TPT requests that
6 The A/B-bit facility scans the originating and terminating subscriber
7 When a loop goes on-hook, the TPT sends the DDL facility a message to
Call processing with UTR
When the original terminal is on an SMS with a UTR, the CM sends the
SMS important information about digit collection. The CM commands the
SMS to start digit collection. The SMS obtains a receiver. The SMS
connects the originator to the receiver. The SMS collects and reports the
digits. The SMS appears in the following figure.
A present UTR does not affect the responsibilities of the line, except in the
following conditions:
When a UTR is present, the SMS performs tasks like the allocation and
deallocation of receivers. The SMS performs tasks like how to make and
free connections. The CM does not perform these tasks.
When digit collection functions are not required, the terminal stops digit
collection. When the terminal stops digit collection, deallocation of the
receiver occurs. From this point, the call continues as before.
297-8231-550 Standard 09.01 August 1998
called subscriber loop.
message to the A/B-bit facility to scan for answers. The A/B-bit facility
directs the A/B-DDL message card to send ringing patterns to the RCS.
confirmation message to the UP ringing task.
subscriber loop. The UP ringing task sends the TPT a message that
indicates the subscriber answered.
the A/B-bit facility scan for on-hook on the called subscriber line.
loops. The A/B-bit facility sends the TPT a message when one of the
loops goes on-hook.
remove assignment from the DS-1 channel. The DDL facility removes
assignment from the DS-1 channel from the associated subscriber loop.
where the digits arrive from
the allocation and deallocation of the UTR channel for digit collection.