Cheaper line rental
But £1.25 dearer than BT because your CID & 1571 are extra 
I rather pay another company for Caller Id than use Bt, just a shame that the money still goes to BT indirectly.
I presume that the 1571 cost is for the more advanced version where you can personalized it. most other land lind service supplier have a basic 1571 for free, not that I activated mine when i moved from BT.
the one problem i do see with ADSLphone service is that you pay rental and all you get is a phone line, you still need to pay for calls, not free calls at all, which is fine if you don't use the landline i suppose.
Last year i asked about a phone service from ADSL24 as I am on their cable and wireless LLU service and they said they did not supply one but they had it on their website. so i went for First telecom and to be honest they do what I want, I see no reason to change, not that I can at the moment anyway.
Happy with my broadband from ADSL24, got no plans to change, even if I did look at Sky a couple of times.
Adrian
Desktop machine now powered by windows 7 pro 64bit , laptop by ubuntu
On ADSL24 using C&W network.