I would like the fellow to call agin to identify himself/herself

unwanted, unidentifying caller.

i got this call and in call they are verifying password by repeating the number

Hello my name is sabine and I live in the netherlands a small country in Europe.
I recieved a call today from this nummer.
It said on my phone that is was from california.
So i didn't andswer. They left a voicemail with a code in it that i have to activated it. But the disturbin thing was i also recieved a textmessages from whatsapp with a code in it and to activated it I had to use a weblink that was also in the message. This messages I've got 10 minutes before they have called me.
( sorry for my english itsn't so good but I hoop you will understand it)

Hello whan i chainged my watsup number    i got a call from this number in a second