Customer has phoned tech support on a PC phone - support guy can of course hear this from the line quality. During the course of the customer explaining the problem the tech support guy suggests rebooting the PC. Oh dear. Record in log - "customer cut off in middle of support call."
Tech Support no longer wishes to deal with the call. Tech Support pretends the customer is no longer audible. 'Hello?' 'Hello?' 'The bastard's hung up' <click> (I've seen this used, with those exact words!) Works with telemarketers, too. "Customers" don't need a reason to hang up on telemarketers. Telemarketers usually don't want to.
Each day, one of the pool of tech support people is designated as supervisor, so that when an irate customer calls and asks for a supervisor, they can be transferred to someone instantly, but without giving them any greater chance of being helped.
Tech Support Tricks