The prohibited phrases and words include more than 50 using "the f-word," and 17 that contain "butt."
Many of them involve homosexuality, including the words "lesbian" and "gay," and some of them are not in and of themselves obscene, including "pimp," "stroke," "stupid" and "flatulence."
While admitting that Pakistan's constitution guaranteed free speech, the Pakistan Telecommunication Authority told mobile phone companies that such freedom was "not unrestricted" under court rulings and they had obligations under their licences to prevent "obnoxious communication."
