I

Figure 11.2-4 Format of parameters. Par.3: backward call indicators. Par.12: forward call indicators. Par. 13: information indicators. Par. 14: information request indicators.

Figure 11.2-4 Format of parameters. Par.3: backward call indicators. Par.12: forward call indicators. Par. 13: information indicators. Par. 14: information request indicators.

Par.2 Automatic Congestion Level. This is an optional parameter in REL messages (Fig. 11.2-3). It indicates congestion at the exchange, and is coded as follows:

0000 0001 Congestion level 1 exceeded (moderate congestion) 0000 0010 Congestion level 2 exceeded (severe congestion)

Par.3 Backward Call Indicators. This is a mandatory parameter in ACM message, and optional in CPG and ANM messages (Fig. 11.2-4). It contains a number of indicator bits with information for the originating exchange:

Bits Bits

BA Charge Indicator

00 No indication

01 Do not charge 10 Charge

FE Called Party Category

00 Not known

01 Subscriber 10 Payphone

DC Called Party Status

00 No information

01 Subscriber free 11 Call set-up delay

HG End-to-end signaling

00 Not available

01 Pass-along method available

10 SCCP method available

11 Pass-along and SCCP methods available

J Interworking Indicator

0 TUP or ISUP signaling all the way (no interworking)

1 Interworking encountered

L Holding Indicator

0 Holding not required

1 Holding required

N Echo Control Indicator

0 Incoming half-echo control device not included

1 Incoming half-echo control device included

K ISUP Indicator

0 Not ISUP signaling all the way

1 ISUP signaling all the way

M ISDN Access Indicator

0 Called party has non-ISDN access (analog subscriber)

1 Called party has ISDN access (ISDN user)

The combination of bits H, G, J, and K is known as the protocol control indicator.

Octets j

0 0

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