Boards
When your boss asks to answer his mobile cos he's on the landline...
...even when the number is recognised (so it's not even a case of 'ask who's calling') is A REALLY ANNOYING THING TO DO.
Because the whole "Mr Boss's phone. Me talking. The Boss is on the landline and will call you back." schtick is utterly pointless. And it always throws the caller off-balance. Why not just silence the ringtone and let the call ring out?