3.4.4 Automatic call clear sequence
An automatic call is cleared when the DTR signal is received from the HSD terminal.
The HSD terminal turns off DTR, then the automatic call is cleared.
The HSD terminal sends clear signal to CES, then HSD modem turns off DCD and CTS. Finally HSD modem turns off DSR.
CES | NCS | FELCOM |
Disconnect
HSUB
CESI
Ch. release SU
Ch. release SU
10 times
DTR OFF
DCD CTS OFF
DSR OFF
Figure 8 Automatic call clear sequence
3.4.5 Call clear sequence from land
Land clears automatic call, then CES sends clear signal. The HSD modem turns off DCD and CTS. Finally, the HSD modem turns off DSR, and the HSD terminal turns off DTR.
CES | NCS | FELCOM |
Disconnect from land
Max. 2 min delay
Ch. release SU
HSUB
CESI
Ch. release SU
HSUB
Ch. release SU
10 times
DCD CTS OFF
DSR OFF
DTR OFF
Figure 9 Call clear sequence from land
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