Prism Service; Call Processing; Translation And Routing - Nortel DMS-250 Reference Manual

Figure 7-9
Calling number not delivered in the SS7 network

PRISM service

PRISM service is the generic service for public calls. PRISM calls are
translated in-switch instead of through the NCS/DAP.

Call processing

If the NSF parameter in the incoming SETUP message indicates PRISM
service, the DMS-250 switch initiates the originating DAL call processing.
If required, the switch performs DTMF digit collection of supplemental code
(suppcode) and/or account code. Depending on the subscription parameters
of the PRI interface, treatment-to-cause mapping may be performed (as
described in Chapter 5, "Call control procedures").

Translation and routing

Translation and routing are initiated by screening the called number in the
SETUP message in the PRTNM field in table CALLATTR. Pretranslator
datafill determines whether the conflict or nonconflict dialing plan is in use.
The standard routing mechanism is then performed by using the STS filed
against the authcode in table AUTHCODM. For more information about
calling number delivery and call type delivery for PRISM service on a PRI,
see "Identifying call origin—calling number delivery" and "Identifying call
type" in this chapter.
Table 7-8 describes the conflict dialing plans supported by PRISM.
(PRI)
PBX DMS-250
SETUP
CALL PROC
ALERT
CONN
CONN ACK
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
(ISUP)
DMS-250
IAM
ACM
ANM (BCSI=01)
Active Call
Feature interaction 7-27
(PRI)
PBX
(CPIALLOW=NO)
SETUP
CALL PROC
ALERT
CONN
CONN ACK