Phone experiment

Would anybody like to help me with an experiment?

So, someone phones your flat or office or whatever; the person they want to speak to isn’t in – what do you say?

My hypothesis is that if you say: “Sorry they aren’t in at the moment, can I take a message?” the caller won’t bother and will hangup before they even give their name.

On the other hand if you say: “Sorry they aren’t in at the moment, can I ask who’s calling?” they’ll leave a message along with their name.