how to detect telephone numbers in a text (and replace them)?

[prohax]

I know it can be done for bad words (checking an array of preset words) but how to detect telephone numbers in a long text?I'm building a website in PHP for a client who needs to avoid people using the description field to put their mobile phone numbers..(see craigslist etc..)beside he's going to need some moderation but i was wondering if there is a way to block at least the obvious like \[code\]nnn-nnn-nnnn\[/code\], not asking to block other weird way of writing like \[code\]HeiGHT*/four*/nine\[/code\] etc...