Unfortunately I cant link to the thread where I saw the discussion since you have to be an (ISP) member to login and view.
Theres a bit of info
here.. that predeceeds the real discussion going on in the Be Forum.
The first answer from Be was the Maritime frequencies but when that was disapproved..
(2174·5 kHz Global Maritime Distress and Safety System (GMDSS) distress and safety traffic by NBDP.)
.... they later came back with this
We carry out extensive testing with our network vendor to produce a fast, stable network. As part of this testing, we have identified a number of frequencies that commonly affect the stability of broadband lines, usually due to significant fluctuation of noise in these frequencies. This can affect the stability of a broadband line. This results in certain frequencies which have been identified as causing significant stability or noise issues being masked out - tones 476 to 499 fall into this category.
Theres been several "debates" as to why that doesnt stand up (the original thread was locked and others opened).
It has been ascertained that other LLU ISPs dont block it.
As yet there has been no response from Be.
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Edit - apologies there was a reply in another thread from Brett after users asked if individual lines could request removal of this block..
We have all had the update from the Network manager and take is our stand on this issue "we will not be unblocking these gaps on request" this is not a service we can offer.
Now this does not mean that we can not revisit this topic later in the year but as for now our road map is full, full of exciting new "services/tools" which have assigned resource’s to launch them.