yep that's right. i'm using smartftp, and the default port is 21.
this is my log
[23:13:20] SmartFTP v2.0.999.5
[23:13:20] Resolving host name "upload.ntlworld.com"
[23:13:20] Connecting to 62.253.162.29 Port: 21
[23:13:41] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
[23:13:41] Cannot login waiting to retry (30s)...
[23:13:41] Client closed the connection.
[23:13:41] Active Help: http://www.smartftp.com/support/kb/index.php/58