User`s guide

1(4)
Datum/Date Rev
Dokumentnr/DocumentnrUppgjord/Prepared
Dokansv/Godkänd - Doc respons/Approved Kontr/Checked Tillhör/Referens-File/Reference
97-10-31 C
487/155 34-ASB 150 02 Uen
FACILITY DESCRIPTION
Faktaansvarig - Subject responsible
SEA/TB/MP T.Preißner
SEA/TB/MP ASB 150 02
SEA/TB/XE
TRUNK CALL DISCRIMINATION
(TCD)
Definition
Using Trunk Call Discrimination = TCD it is possible to
determine (program) to which area (routing number)
codes the extensions shall be permitted to ring.
Also incoming trunks can be checked.
Permitted area codes are placed in a table that, for
outgoing external traffic, is compared with the number
dialled by the extension and the extension's external
number category.
Use
TCD provides the possibility, in a flexible manner, to
restrict the possibilities of extensions to make
expensive calls.
Operation
For outgoing external calls each dialled digit is
compared with those number intervals that, are to be
checked in accordance with the extension's or trunk's
external number category.
The check is made according to the following rules:
• Dialled digit exists in the table.
No more digits are to be checked.
THE DESTINATION IS OPEN, TCD IS DISCON-
NECTED
• Dialled digit exists in the table.
More digits are to be checked.
WAIT FOR MORE DIGITS
• Dialled digit is not in the table.
THE DESTINATION IS BLOCKED.
The trunk will be disconnected and marked free.
The direction is blocked for the caller who re-
ceives congestion tone
Capacity
Permitted destinations are stored in a table compiled
on the basis of number intervals.
A number interval can be two arbitrary digit
combinations, where digit combination 1 must always
be lower or equal to digit combination 2.
Example of number intervals
• 1 - 6
• 71 - 79
• 01234 - 01238
• 00942 - 00942
If a number interval is programmed as 2 - 4, this
means that all destinations that begin with 2, 3 or 4 are
open.
100 number intervals (00 - 99) can be programmed.
Each number interval can have a discrimination depth
of up to ten digits.
Extensions and trunks can be assigned one of nine
TCD-categories (0 - 8) for day traffic and night traffic.
If an extension or a trunk is assigned category 0 this
means that no check will be undertaken.
For each number interval is stated which of the TCD-
categories 1 - 8 shall be compared with the interval.
When the system is switched for night service, the
check (comparison) is made against those intervals
that correspond to the night service categories,
otherwise against the day service categories.
Limitations
Extensions belonging to group 0 are fully open for
external traffic, that is they are not subjected to TCD-
analysis.
External numbers not entered in the table are blocked
for all extensions except those with category 0.
Calls made with the help of common abbreviated
numbers are not checked by the TCD, whereas
individual abbreviated numbers are.
487.fm
Database reference