Q

Exchange R

Called

User

Information (O)

Par. 5 Called Party Number (M)

Par. 7 Calling Party Number (O)

Par. 1 Access Transport (O)

Par. 6 Calling Party Category (M)

Par. 15 Nature of Connection Indicators (M)

Par. 12 Forward Call Indicators (M)

IE. 11 Progress Indicators (O)

Figure 11.3-3 Mappings of Q.931 SETUP messages and ISUP initial address message (IAM). Note: (M) mandatory parameter or IE. (0) optional parameter or IE.

Mapping of ALERT and ACM Messages (Fig. 11.3-4). The ALERT message received from user U2 normally does not include IEs. The corresponding ACM messages include a Par.3 (backward call indicators), whose values are set by exchange R. Par.3 is processed by exchanges Q and P, and under certain conditions, an indicator is mapped to an IE. 11 (progress indicators), which is included in the ALERT message to user U,.

Mapping of DISC and REL Messages (Fig. 11.3-5). DISC and REL messages are general-purpose requests to release a B-channel or a trunk. They

User

Exchange

0 0

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