Was on Be, lured by the deal a Sky reseller offered: half price line rental, half price fibre, free tv for a year. Router Sky deliver doesn't support SIP, wasn't keen on cracking the broadband username/pass out of the it and violating their Ts&Cs which insist you use their kit. Submitted for a change to BT less that a week after start date.
Bit of a hassle, but the upshot is I keep the free tv service for a year... profit?