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4.3 EXAMPLES
Examples of calling (transmitting) and answering (receiving) one page using fax class 1
commands are shown in Table 4-4 and Table 4-5, respectively. The examples show the
interchange between the DTE and the modem for various cases.
Comments are included to explain how to handle various situations. Commands and
responses are in upper case (e.g., AT+FRH=3) and comments are in lower case. All
streams of data denoted by <..frame> are terminated by the <DLE><ETX> characters.
Table 4-4. Fax Class 1 Calling Sequence (Transmitting a Single Page)
DTE Commands Modem Responses Local Modem Action Remote Station Action Notes
AT+FCLASS=1.0 OK Set Class 1
ATDT<string>
CONNECT
<NSF frame>
<DLE><ETX>
OK
Dial and send CNG
Look for V.21
Detect flags
Answer
send CED, V.21
Send HDLC flags
Send NSF frame
AT+FRH=3
implied by dialing with
+FCLASS=1.0
AT+FRH=3
CONNECT
<CFI frame data>
<DLE><ETX>
OK
Detect flags
get CSI
get FCS
accept FCS
send CSI frame
check FCS Frame status OK
AT+FRH=3
CONNECT
<DIS frame data>
<DLE><ETX>
OK
Detect flags
get DIS
get FCS
accept FCS
send DIS frame
check FCS
DTE must detect final
frame bit to anticipate
loss of carrier
AT+FRH=3 NO CARRIER detect loss-of-carrier drop carrier
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