Listening in: can call centres hear you when you’re on hold?

If hold music is playing, it's almost certain no one is tuning in. But if there's silence on the line, watch what you say

Customers going to the toilet, eating, smoking a bong and, of course, cursing the company - these are among the notable sounds call centre workers say they've heard when callers thought no one could hear.

After a breakfast TV host aired claims that staff at Air New Zealand's call centre could hear customers who were on hold, the Guardian asked call centre expert Justin Tippett if that was indeed possible.