442033180712
called constantly more than 20 times, stating he was Windows Security Centre.
I AM a qualified Computer Tech, and when I told this scammster this he just laughed, especially after I mentioned getting government line tracing if calling again.
and promptly kept calling back... I then tried to change my voice accent when answering the call -
Metropolitan Crime Branch. This call is being traced !
he called back a couple more times , as private call and again as the displayed number, each time I answered as
Metropolitan Crime Branch, This call is being traced !
They have not called again.

Somebody I know only a few days ago must have had same callers, and was not knowledgeable of these scammers ,
they logged into their computer, and followed the instructions of the caller - and unfortunately then watched helplessly as the hacker got into his bank account and drained it , then locked up the computer and disappeared ... computer also now code locked not usable!!!!
BE WARNED these callers ARE dangerous !!
PS
according to reverse phone look up
the prefix
44203 is possibly in the London area...
but good chance they are using routing software to disguise actual call id.
caller had strong Indian accent - so could be calling from anywhere in general, and possibly using something like skype with speed redial.
19-Feb-2018_Australia.

Same as above claiming to be from Microsoft, but an international search suggests they have multiple scams.

Scam Phone Number 442033180712, A woman posing as a Computer Expert from Microsoft Windows Support