5-4 Call control procedures
297-2521-106 Standard 23.01 March 2001
•
determining the routing characteristic of the call (including called party
number and bearer capability)
• routing the call
Call types supported
The following call types are supported by the DMS-250 switch:
• calls coming into the switch—Virtual Network (VNET) and PRISM
• calls going out of the switch—VNET, service access code (SAC) calls
(for example, 8xx and 900), and PRISM
For more information about these call types, see Chapter 7, “Feature
interaction.”
Network control system
The network control system (NCS) is a centralized, remote system of
databases (called database access points or DAPs) owned and operated by
MWC. NCS provides the DMS-250 switch with call verification and call
translation information for the following calls:
• VNET
• SAC
• Calling card
The DMS-250 makes various requests of the NCS for its services and waits
for the NCS to respond. The information the NCS returns to the switch is
used for:
• call translation
• account/supplementary code validation
• card number validation
• routing
• billing and/or retranslation
• specialized or customized treatments
Call authorization
Basic authorization identifies the subscriber, prevents unauthorized access to
the network, and enables the call to be billed to the subscriber.
Authorization code
The switch retrieves the address from the incoming SETUP message to
authorize the call. The authorization code is retrieved from table
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