AOpen FM56 Manual page 100

AT+FRH=3
<TSI frame data>
<DLE><ETX>
<DCS frame data>
<DLE><ETX>
CONNECT
CONNECT
OK
send V.21 carrier
send flags
send TSI frame
send FCS
send flags
send DCS frame
send FCS, flags
drop carrier
detect carrier
detect flags
get TSI frame
get DCS frame
Final frame bit clear tells the
modem to expect another
frame.
Final frame bit set tells the
modem not to expect another
frame
AT+FTS=8;
+FTM=96
<TCF data pattern>
<DLE><ETX>
CONNECT
OK
wait 80 ms
send V.29 carrier
send TCF data
drop carrier
detect carrier
get TCF data
AT+FRH=3
CONNECT
<CFR frame data>
<DLE><ETX>
OK
detect carrier
detect flags
get CFR frame
check FCS
accept FCS
send V.21 carrier
send flags
get CRF frame
send FCS