From: Martin Meredith <mez(a)ubuntu.com>
Sky broadband DO actively block VoIP. I bought this up with them and
they faffed around the issue until I went away.
I am visiting the UK at the moment and am a guest at house with Sky
broadband and have had no problems at all with Skype - well apart from
all the usual ones :) If Sky do actively block Skype they don't seem
to be very successful.
Steve