cell phone unlock car door

I heard a tip that if you accidentally lock your car key in the car when shopping at Walmart and you have a spare key at home and your wife is at home, your wife can use cell phone to help unlock your car remotely. The car key needs to have remote button. It works as follows. You and your wife are talking over cell phone, your wife use put spare key near cell phone and push remote button, you put your cell phone close to the car, the door will be unlocked.

I searched online. There are some articles which doubts this method. I think it can be easily tested. My wife and I had some experiments for our Prius. It works for Prius.

A good friend of mine had the exact problem. He did not know this tip and had to pay for taxi driver twice for the round trip between the shopping center and home.

Note that this is not an app of smart phones like Android, Blackberry or iPhone. This is the functionality of the regular cell phone.