It's not the first time I've seen this article online. Great advice, yet there are some flaws in this article. If the front desk staff is properly trained, more should be done first before they transfer the call.
THE FRONT DESK - the MUST DO: - If the staff is trained properly, they will look after your safety, no doubt about it!
1. ASK who are they looking for - specifically by name; don't just transfer the call because someone asked for a room number,
2. Tell caller you need to announce their name to your guest
3. Inform your guest that this is an outside call.

If that's missed, THE GUEST also MUST DO the following:
1. ASK - on arrival to get the front desk personnel's name on duty (FYI)
2. Once the call comes trough, ASK - who are you speaking with.
3. ASK: Who are they looking for - if they don't even know your name, that's a FLAG,
don't answer any more questions.
4. When you realize that's not legitimate, hang up immediately and you call the front desk and have a conversation and report the incident.
I feel that this article is a little more complete with all this additional info. Happy reading!
Travel Safe. Stay Safe.