Pri Origination And Call Type - Nortel DMS-250 Reference Manual

LTCALLS table
The LTCALLS (Logical Terminal Calls) table contains the ISA data for all
call types on a PRI. Each PRI call type has a unique entry in this table and
contains the following information:
CALLATTR (call attribute index)—indexes into table CALLATTR. This
index provides a means whereby a separate translations environment can
be assigned to each of the ISA call types (that is, separate pretranslators
and STSs for PRISM and VNET).
ISA routing information—an alternative to interexchange routing.
Individual call types can be routed directly to an outgoing trunk without
first passing through translations and screening. See "Translation routing
options" in this chapter for more information.
CALLATTR table
This table (accessed from table LTCALLS) specifies all of the translations
and screening information necessary to process PRI calls. Figure 7-1 shows
the relationship of these two ISA subscription parameter tables. Each entry
in table CALLATTR is a set of translation and screening parameters for a
specific logical terminal identifier (LTID) and call type.
Figure 7-1
ISA translation table relationship
LTID and
CALLTYPE

PRI origination and call type

Normally the Network-Specific Facilities (NSF) information element (or
parameter) determines the originating call type. This element is in the
incoming SETUP message from the originating PRI. (If no NSF information
element is received, call type is determined by the NSFDFLT field in table
TRKGRP.) After the originating call type is determined, call type
information is passed to the terminating PRI directly in the NSF information
element of the outgoing SETUP message.
PRISM
If the incoming NSF information element is set to PRISM, the call is treated
as a public call type. When the NPI in the called party number information
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
ISA direct routing attributes
LTCALLS
CALLATTR INDEX
Feature interaction 7-3
Translations
CALLATTR
attributes of
originating PRI