In almost every case, no one from a cryptocurrency related product or service will call you. In a case where they would call, they will never ask for your private keys, secrets, seeds, and passwords. Further, this sort of information should not be given out under any circumstances (not by email, not in a support ticket, etc.).
NOTE: For an example of others warning of this type of crypto telephone phishing scam, see the following Tweet by Ledger (who makes the Nano S, a popular hardware wallet).
WARNING: Ledger does NOT provide customer support over the phone. Beware the scammers impersonating the Ledger support team by using 1-888-XXXX (or others) phone numbers. Don’t give control of your computer to strangers and NEVER reveal your 24 words to anyone!
— Ledger (@LedgerHQ) March 1, 2018
In other words, if someone calls you and says they are from Ledger or Coinbase or whatever, it is a giant red flag, and there is a high probability you are getting “phished” (that is, the person on the phone is trying to get personal information from you).
If you think the call is real, you can always call them back. You can go and check the official website and figure out their policy, contact their support by opening a ticket, etc. (make sure to double check the URL you are using to ensure you are going to the official site).
There is no reason for customer service people from cryptocurrency related products and services to call you.
If you get a call like this, one that might be a scammer, it could be something simple. For example, you posted in a crypto group with your Facebook, and you have your number and name as public information there (or somewhere else). Or, it could be something more complex, like writing information on a malicious web form.
If you do get this sort of call, smart precautionary moves include:
- Not giving them any information.
- Reporting their number (see //www.consumer.ftc.gov/articles/0076-phone-scams).
- Reviewing the type of information you have displayed publicly online.
- Considering your web history to find out if you could have entered your information on a malicious site.
- Changing passwords of websites and making sure you have 2-factor authentication on.
With that covered, if someone is calling you trying to phish for information, it implies that there is a good chance they lack the information they need to cause you serious headaches. Give them nothing and then take some extra precautions just in case.