User`s guide

AT Commands
Modem 3600 5-23
If the screen shows no characters, enter the E1 command to turn modem
echo on or enable local echo on the terminal.
Online Character Echo F
In some lower speed modems the F command determines if characters
are echoed to the DTE from the modem when online. This function is
generally controlled by the communications software. The modem does
not support online character echo.
Hanging Up H, H1
To end a call, enter the H command. This tells the modem to disconnect
and go on hook. The modem must be in command mode to use this
command.
Enter the H1 command to take the modem off hook. The modem
automatically goes off hook when a dial command is keyed in.
Fast Disconnect H2, H3
The results of the H command can be modified by the H2 and H3
commands. H2 or H3 will not cause a hang up but will affect the method
of hanging up the next time the H command is issued. If H2 is entered,
the H command will hang up according to CCITT V.32 standards. If
operating in V.32 bis mode the H2 command could take several seconds.
If H3 (the fast command) is entered, the H command will hang up much
more rapidly at those speeds.
Command Operation
E Echo off
E1 Echo on
Command Operation
H The modem hangs up.
H1 Forces modem off hook
H2 Sets H command to normal hangup procedure (long
space, cleardown, protocol)
H3 Sets H command to fast hang up