AT&T MERLIN LEGEND Release 4.0 Feature Reference page 412

Feature Reference
PRI calls, support for Station Identification/Automatic Number Identification
(SID-ANI) as a Calling Party Number, and Dial Plan Routing.
Terminology
Called Party Number (CdPN)
In general, the term Called Party Number (CdPN) is a telephone number that
was dialed to reach a destination. However, while routing the call, the network
can change the Called Party Number to make routing easier. In either case, the
network sends the Called Party Number to the system when a call arrives at the
system.
Calling Party Number
If you subscribe to the AT&T INFO2 Automatic Number Identification (ANI)
service, an incoming call on an ISDN line includes accompanying information
about the party placing the call. This can be either a station (extension)
identification (SID-ANI) number that is defined by the internal dial plan of the
system where the call originated (
(
information, a call recipient may identify the caller before answering.
Lines/Trunks
In this section on PRI and T1, lines are the representations that appear on
extension sets or are put into pools. They represent the type of service
requested on a call. Trunks are the facilities that link switches. For all except
DS1, lines have a one-to-one correspondence to trunks, since there are 24
transmission channels for each DS1 connection. With PRI, lines are further
removed from trunks because the type of service is not linked to the B-channel
(trunk). The system has an intermediary, called a B-channel group (BCG). Lines
are used to place and receive calls, and a BCG links B-channels to lines.
B-channel groups may be a single B-channel or multiple B-channels grouped
together.
Figure 34 shows how lines, B-channels, and B-channel groups, function
together. For outgoing calls, the user selects a PRI line that routes the call to a
B-channel group. The BCG selects an open B-channel and connects over the
PRI connection. For incoming calls, the network selects an open B-channel and
the BCG directs the call to the PRI line for which it was intended by matching
Called Party Number with the line's administered telephone number. In addition,
the Dial Plan Routing feature may be used to further direct the call to a specific
station (SA button) or Calling Group by matching some portion of the Called
Party Number against the system dial plan. Dial Plan Routing is similar to Direct
Inward Dialing.
Each DS1 module is given 24 lines, regardless of whether or not it is used for
emulation of trunks or for PRI.
412
Primary Rate Interface (PRI) and T1
), or both (
), or billing number information
). With this