Number Witheld.
Most of the time I get calls from 'Microsoft Support', the number is withheld.
I'd love to put a call blocker on my line but most of the NHS has moved to calling with 'Number withheld' all in the interests of patient security.
I learned a few choice swear words in Hindi that question the callers parenthood for these people calling from MS.
Other calls get answered with 'what are you trying to sell me?' That gets rid of most of them.