Dialogic 6.2 manual Isdn Call Clearing Initiated by Module, Isdn Overlapped Dialing, November 323

ISDN Call Processing Overview

ISDN Overlapped Dialing

The Euro-ISDN protocol only allows 20 digits to be sent as a group (en-block) when placing a call. For longer phone numbers, the application must use overlapped dialing— the process of sending extra digits after the initial call setup. This process allows:

„The application to dial very large phone numbers

„The remote end to start answering a call before it receives all the digits

The Bfv API automatically performs overlapped dialing on Euro- ISDN outgoing calls using E1 or BRI lines when the phone number is longer than 20 digits. Users will be able to place a call with up to 255 digits in the dial string on Euro-ISDN without requiring changes in the application.

Applications automatically send overlapped digits when the user calls BfvCallSetup, BfvLineDialString or BfvLineOriginateCall and provides a dial string of more than 20 digits when Euro-ISDN is being used.

The feature divides the dial string into banks of 20 digits and uses the overlapped dialing feature in Euro-ISDN to send one block of digits at a time.

ISDN Call Clearing - Initiated by Module

Atypical module-initiated call clearing (tear down) sequence is illustrated in Figure 50. The following message exchange is relative to the module:

1.The host initiates the call clearing procedure by sending an L4L3mCLEAR_REQUEST message to the module.

2.Upon receipt of the L4L3mCLEAR_REQUEST message, the module sends a DISCONNECT message to the network.

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