[SFTF] Test case 803

["Michael Procter" <michael.procter@xxxxxxxxx>]

I tried to run case803 (Media on-hold), and found a problem
in NetworkEventHandler.py.  The function checkMediaSocket
contains the line:

        if not isinstance(sock, socket):

which I believe should be:

        if not isinstance(sock, socket.socket):

At least, with this change, the test case runs as I expect
without giving any runtime exceptions.  Can you confirm the
fix and check it in please?

Regards,

Michael Procter