I've got a Nokia 6310i, it was 3rd hand when I got it in 2004, I think it's a 2002 model at least, if not older. It's a great simple phone, monochrome screen but slim and quite robust. Apparently they sell for over a hundred quid on eBay these days because they're so popular with businesses and they no longer make them.
Before that it was a Motorola M3788 brick that a friend gave to me, by the time I received it the aerial was broken off, it had fire damage in one corner after a fire-walking incident and it had been dropped repeatedly. It even survived a swim in a pint glass and an impromptu football match with it briefly starring as the football. It's indestructible. They'll dig it up in a thousand years and it'll still work once charged