If you’re running into trouble with the CALL command on your FTP server in Android, it might be because many Android-based FTP apps don’t fully support advanced FTP commands. You could try using a different FTP client (like AndFTP or FTP Server Pro) and check the server logs for details. Also, make sure the command syntax matches what your specific FTP server implementation supports.

Thanks, I finally use WinSCP for file transfers and PuTTY for the commands.

What does the log show? What were you trying to do?

Thanks Martin,
Following your instructions, I used FTPserver ultimate and herewith the log.
Unfortunately no success either.

You cannot call WinSCP scripting commands (call) in the Console window.

You cannot call remote shell commands (pm) over FTP protocol.

Except if the FTP server have a special extension (e.g. SITE EXEC) that would allow you to do so:
SITE EXEC pm install my.apk

Use SFTP/SCP protocol, if possible.

I am running WINSCP client on Windows 7 with FTPServer(Android app) on Android.
My intention be to possibly install an apk on Android from my Windows client.
I opened a terminal-command on the Server(Android) and tried to run:
call pm install my.apk
Then
call mdir try (ftp command set)
I receive "500 CALL not understood
The only command doable is "pwd".
Any hints?
Thanks.
Nikos