Worth a watch. Great Spanish film from 1972 - has some interesting, twisted purchase on the imagination - something to do with the fear of technology, alienation, anonymity, the city, faceless corporations, powelessness, paranoia, fear of modernity, loss of connection - the phone - the symbol of connection?, becomes the glass box/coffin/goldfish bowl...echoes of other '70s themes including later films like 'Duel' and 'Coma'. And perhaps also an existential parable
An update (March '10) - the film has disappeared from YouTube, a bit like the bloke in the telephone box, but here's a documentary/commentary from Spanish TV about it...followed by the film in full. Totally worth watching. Mesmerising.
Update again (October 2014). Back on Youtube and in full. New link added above.