Dialogic 6.2 Manuale Utente

Using the overlap_rcv feature of L4L3mENABLE_PROTOCOL

November 2009

328

Using the overlap_rcv feature of 
L4L3mENABLE_PROTOCOL

When an ISDN call is received from the Public Telephone Network, 

the caller information arrives in a Q.931 SETUP message. Typically, 

this SETUP message contains all the information necessary for the 

user to properly route, switch and/or complete the call: information 

about the type of call (voice, modem, data, and so on), caller ID 

information, and so on.

Overlap Receive mode occurs when the incoming SETUP message 

contains no CALLED party information, or incomplete CALLED 

party information. The CALLED party information is necessary to 

complete a circuit-switched call, because it identifies the complete 

number that the originator is dialing.

The ITU Q.931 Recommendation defines a SENDING_COMPLETE 

Information Element as an indicator of when a SETUP message has 

complete CALLED party number information. If a SETUP message 

is received and there is no SENDING_COMPLETE info element in 

the message, the user is expected to enter Overlap Receive mode.

RESTart ACKnowledge

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SEGMENT

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CONGestion CONtrol

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INFOmation

INFO_REQUEST

INFO

NOTIFY

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UNIVERSAL

STATus

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STATUS_IND

STATus ENQuiry

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FACILITY

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UNIVERSAL