...if the bombs fell in 2077, how come everyone are wearing 50's clothes?

Because it's in the USA. :p

It is a science fiction world in the style of the 1950s, as if they were written back then.

As far as I know it's a different timeline, where the world turned out more like people imagined it would in the 50s, for example nuclear powered cars. Which is why the derelict cars in F3 blow up in such a spectacular fashion when destroyed.

the only clothing shops that survived were 50';s retro boutiques XD

Actually nuclear powered cars are quite new in the timeline of Fallout they appear only after oil sortages. But yes I agree with you the whole universe is made in the style of 50s futurism. I have book from 60s thats mostly about historical transportation but a part of a book is about future designes and let me tell you thoose look like something out of Fallout design book.

2076 was a year that the fifties made a comeback and by 2077 even the music was from the thirties:-)

It's a retro-futuristic alternate universe, themed around how the 50's imagined the future. Culture stagnated before the bombs fell.

Note that the hand held device, the Pip-boy isn't a phone, and never was intended to be. The 90's never happened in that alternative future.

Canonically the first point of separation is that the transistor wasn't discovered, thus computers ran on vacuum tubes for much longer, and the information economy never really developed. Since the U.S. never buried the USSR economically the Cold war went a lot longer, peak oil hit faster, society was a lot more militarized, and stagnated due to fear, never really breaking out of the Fifties mindset.

Couldn't have summed it up better myself. Interplay wanted a 'Jetsons' kind of feel to the game, with a 50's 'future of tomorrow' vibe.

The closer thing to a phone that I remember finding in the classic Fallouts, are the camoufagled radios. One of the people that uses them to communicate is the leader of the slaver's guild, Metgzer.

The only long distance conversation you can have is that one in the Gecko's nuclear power plant, in the computer that can activate the maintenance robot.

It's a fun conversation! ;)

You can't use the radio to talk with people, even if the radio is fine (like the one Vic fixes).
That's only possible in the fan-made game called Fonline 2238, where it can be used to talk with other players, that aren't present in your current location. I mean, it was possible, before the server got shut down. But I believe it's possible to do that in the newer MMO, called Fonline Reloaded. http://www.fonline-reloaded.net/