BT8600 call blocker phone "offer"

[#1]

I wonder what the difference is between the "offer" for PlusNet members for the twin set (actually all the sets):

http://www.shop.bt.com/other-pages/landing-pages/plusnet-bt8600-offer/

and the same set, cheaper, in Amazon:
https://www.amazon.co.uk/BT-Cordless-Phone-Answer-Machine/dp/B01BWMWTM6/ref=sr_1_2?ie=UTF8&qid=14735...

[#2]

It's all done in the telephone base station so best price must be best option I would think. They work briliantly and in my case I've gone from several calls every day to zero calls. 100% success!

There is a ongoing cost as you have to pay for the caller display add-on.

[#3]

Got ya ☺️
Thing is, if they are exactly the same, it's not much of an offer if you can get them elsewhere for less!

[#4]

Yup... agreed.