Dialogic 6.2 Manuale Utente

Using the overlap_rcv feature of L4L3mENABLE_PROTOCOL

November 2009

330

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.

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.