Two-factor authentication is probably the best solution -- unless your phone is at the bottom of the river, or your employer puts you in a spot where phone service is non-existent, like the basement.
Some services (ie Google) allow you to have a backup phone number. So my advice is buy yourself a cheap Android phone with a pay as you go SIM just for these types of situations. It's cheap insurance. Some people even use a freedompop sim which is totally free. So $50-$100 onetime cost for the phone and $0 monthly cost.
So yes, if someone tells you've they've committed a crime or are going to commit a crime you are obligated to report it to law enforcement and refuse the transaction.
That's certainly not universally true.
'Oh! I know! We'll stack another layer of software on top! That'll just fix everything!'
Reminds me of one of my favorite quotes:
"All problems in computer science can be solved by another level of indirection"
Knowledge of a crime without reporting it is called accessory. Even if they tell you about the crime after they've done it you are still an accessory after the fact.
Not exactly. You'd have to help conceal the crime to be charged with accessory after the fact.
The next person to mention spaghetti stacks to me is going to have his head knocked off. -- Bill Conrad