To avoid the burden of analysing the crap they tell you, just don't validate yourself to/for anyone who (is contacting you and) hasn't validated him/herself to you first ("
And who trusts you?"
). No, you can't rely on the number they call from detected!
These days it's best to never talk on serious matters using an incoming call at all. It might even seem it's someone you know personally... Always call back, using the correct number to make sure.
By the way, it might be not the case yet, but it can be expected that "smart" phones' software will be able to implicitly redirect (substitute the target number of) the outgoing calls too. What's the oldest phone you can use (for your safety)?
Biometrics technologies (or their usage) don't look convincing/reliable/safe. Collecting your data of the kind and using it without your consent would be an absolute outrage!
Note that pretty much anything you say can be used for your voice id,
never say "yes" for your safety!
