User guide

28 RealCT Direct API Developer Guide
Chapter 2: Digit Handling
Group B Signals
The incoming register sends Group B signals after sending A-3
or A-5. The Group B signals provide information about the
subscriber’s line. Table 10 shows the meanings of the Group B
signals.
Table 10. Group B Signals
Signal Meaning
1 Spare for national use
2 Send special information tone
3 Congestion encountered after changing from Group
A to Group B signals
4 Unallocated number
5 Subscriber’s line free, charge
6 Subscriber’s line free, no charge
7 Subscriber’s line out of order
8 Spare for national use
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12
13
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