@ Kitz,
Here's a short summary for Kitz & any who can shed any more light on the quagmire !
BT Wholesale web site will always provide a VDSL speed estimate on all lines connected via their exchange equipment. N.B. This excludes full LLU providers such as TalkTalk**, but BT then estimate using a postcode. All CPs have estimators too but for many low estimate services they just refuse to offer a service. ** Conversley BT Wholesale will estimate for O2 or Be, I believe, because they don't use their own LLU phone service.
The BT Wholesale estimator rejects all very poor services by saying 100 KiloBits per sec up & down. I know of long stretches of lousy cable where nobody can achieve anything, yet some have ADSL 2 services running around 2 Mbps.
The grey, if not totally foggy, area is what the lowest estimator figures that a CP will attempt to offer a service, usually with no speed guarantee at all. Some seem to use the 12 Mbps figure, whilst others will attempt right down to 5 Mbps.
Come the installation day, the BT Openreach engineer will not proceed if his test equipment detects a line fault which the client often has to organise a repair visit by a different Openreach engineer. The VDSL appointment has then to be rescheduled via the CP.
If the line testis O.K. then BT Openreach will attempt the installation PROVIDED the speed at the house exceeds a minimum which might be the 12 Mbps figure if a strict interpretation of the rules is being followed. However if the sun is shining & copious quantities of tea & bacon butties, tea cakes etc. are available, most engineers seem content to complete a minimum speed installation of 5 Mbps.
Perhaps BS & others might please comment / confirm my understandings ?
Kind regards,
Walter