Do you think it would be simpler just to get a new number? You can ask your provider to do that but I am not sure of the implications of your broadband. However, have you thought about giving TPS a call maybe?
http://www.tpsonline.org.uk/tps/contact/
Tel 020 7291 3320
Fax 020 7323 4226
Email
tps@dma.org.uk
Web
www.tpsonline.org.uk
They may be able to do something, its worth a shot I guess. Especially with a little one in the house.. that would just do my nut in
Edit: Forgot to say, Ask SKY to turn on the system that doesn't allow anoymouse numbers to call you. That will put an end to it!