[kalee20]

Originally Posted by rambo1152

...I can enlarge on the "storage" aspect.

BT used to supply an enhanced 1471 service called "1471 Extra" that
listed the last five calls. It was quite useful but it was withdrawn 10 years ago without any explanation.

I formed my own theory that maybe OFCOM thought BT were not honoring the withheld flag sufficiently. The service gave you slightly more
information about "withheld" callers than was possible by other
means, including a caller display.

Say someone called you withholding their number. You speak to them so
you know who it was.
1471 extra will say "The caller who withheld their number called today
at [some time]"

Later in the day they call again, still withheld. Perhaps there was
some malicious content this time, but the point is you don't know
who's calling, but, 1471 now says:
"The caller who withheld their number called today two times. The last
time was at [some_later_time]" So now you *do* know it was from the
same number as the previous call.

I wonder if this was the real reason the service was withdrawn?

I am sure that recording calls-received numbers takes place, as far as possible (calls from abroad may not be possible, for instance), in the aid of crime detection and nuisance-call reduction.

Given that calling numbers are recorded, it was simple for BT to implement the 1471 service. I've found it very useful in the past.

If an ex-directory number calls you - or caller withholds their number, then a flag is passed to the 1471 workings, so the message is, "You were called on (date) at (time). The caller withheld their number." But the caller's withheld number is still stored, and can be made available to the right authorities.

If there really is no number stored - such as internationally-originated call, the message is, "You were called on (date) at (time). We do not have a number for this call." Which is subtly different.