Hi James, I think it's a matter of your python interpreter, because the message is returned by the python's socket class[1]. To check this, try to evoke the url for sending messages from a web browser and see what will you get as a response from the sendsms cgi-bin. If it's "0: Accepted for delivery" and messages are send and received successfully I don't think that this is a Kannel issue.
[1] http://epydoc.sourceforge.net/stdlib/socket._fileobject-class.html BR, Jovan