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the user guide of the SOPHO-LAM P375 and the modems used.
C.3.1. Incoming Call
When DTE-B activates CT108, MODEM-B sends a carrier over the line to MODEM-A. When
MODEM-A detects the incoming carrier, it answers the call automatically and activates both
CT107 and CT109 (CT108 of MODEM-A is continously ON). CT107 is connected to CT108
of the SOPHO-LAM, so the SOPHO-LAM knows that MODEM-A is ready and the analogue
connection is established.
• Call request to SOPHO-LAM
The call request and clearing operation of the SOPHO-LAM convertor depends on the
data parameter settings. For example, one of the following data parameters settings can
be used:
-
CT105 initiates call request;
-
CT103 initiates call request.
When CT105 is used as call request, the carrier of MODEM-B initiates a call request via
CT109 (DCD) of MODEM-A. In this case the connection between DTE-A and the
SOPHO-LAM convertor is cleared when the leased line connection is out of
synchronisation. Note that CT105 can only be used as call request provided CT108 and
CT107 are ON.
When CT103 is used as call request, DTE-B can initiate a call request by typing some
characters. Note that CT103 can only be used as call request provided CT108, CT107,
CT105 and CT106 of the SOPHO-LAM are ON.
After the call request the SOPHO-LAM establishes a connection to a fixed destination.
The SOPHO-LAM uses either Predefined Destination Dialling, the hotline facility or
keyboard dialling.
• Call clearing
In both situations (CT105 and CT103 as call request) the connection between DTE-A and
the SOPHO-LAM can be cleared using one of the following methods:
-
data guarding;
-
break sequence initiates call clear;
-
hang up with Hayes command ATH0.
The SOPHO-LAM can be programmed to use data guarding. Use menu option `Data
guard active' or `Data guard on incoming call active' (please refer to the Customer
Engineer manual of the SOPHO-LAM P375). In this situation the SOPHO-LAM clears the
call when there has been no activity on CT103 and CT104 for a period of time (data
guarding time in minutes). It is also possible to check only the activity on CT103 after an
incoming call has been answered (data guarding time in seconds).
In asynchronous transmission calls can be cleared when a break sequence is detected at
the speed set in the Transmission Speed menu. Use menu option `Break Initiates Call
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