Hello Fire Juggler,
I am not sure if anyone here has used or uses O2 Home Phone, I wouldn't usually recommend or suggest other sites but in this instance I'd suggest it maybe worth checking out the O2 Customer Forums on the main O2 UK site, and also ThinkBroadband.com
both of those sites I am a member of, and they have a wealth of info on BOTH O2 Home Phone and O2 Broadband.
If you need any more info please don't hesistate to PM me via the Private Mesage button or reply on here...