Luckily people do abide to switching their phone to silent or switching it completely off at the movies in Bristol or so I have observed every time I have been which is great but I do agree with the loud one sided shouting conversations on buses. It's as if the person on the phone intends to inform the whole bus about every juicy detail of their lives. Equally I hate business men who make a working call on holiday or at a seaside beach telling every detail and conveying to everyone how important they are. So much for confidentiality and family quality time!