Dialogic 6.2 manual November 330

Using the overlap_rcv feature of L4L3mENABLE_PROTOCOL

How Overlap Receive Mode Changes

Call Control Events Presentation

Volume 5, Bfv API Reference Manual describes the normal call control events associated with ISDN Call Processing and Management. These events occur when incoming SETUP messages contain all the appropriate CALLED_PARTY information elements and SENDING_COMPLETE information elements.

When the overlap_rcv flag is enabled and the SETUP message arrives with incomplete CALLED_PARTY information, the call control events change as follows:

1.Network presents SETUP message to the module, with either incomplete CALLED_PARTY information element present, or no SENDING_COMPLETE info element present.

2.Instant ISDN activates the T302 timer, sends a SETUP_ ACKNOWLEDGE message to the Network, and enters the Overlap Receive state. Instant ISDN also presents the initial call information to the Host in an L3L4mSETUP_IND message.

Note: The T302 timer is under Host control (see IISDN_Q931_ TIMERS in the IISDN.H header file) with a default timer value of 15 seconds.

3.The Network sends the remainder of the call information (if any) in one or more INFORMATION messages. Each information message arrives as an L3L4mINFO event to the Host application, which contains CALLED_PARTY information elements, as well as an indicator for SENDING_COMPLETE information elements. Each time an INFORMATION message is received without a SENDING_COMPLETE info element present in the message, Instant ISDN restarts the T302 timer.

4.Presence of the SENDING_COMPLETE information element is optional. Some ISDN switches and dialing plans will present all of the CALLED_PARTY information and never send a SENDING_COMPLETE info element in the final INFORMATION or SETUP message.

5.When the final INFORMATION message has been received (indicated by presence of the SENDING_COMPLETE information element, or when the host has determined that the CALLED_PARTY information is sufficient to complete the call), the Host application issues an L4L3mCALL_PROCEEDING and the call control events will then transpire normally.

November 2009 330