"To give someone the 411" is short for information but is this phrase common in the US and/or in Britain and is it still up to date or outdated?
The urban dictionary has a definition for it, which is probably a good barometer for its utility in AmE slang. I'm from the western USA, and it doesn't strike me as outdated. It is, however, becoming more and more trite after movies like Clueless ("Here's the 411 on Mr. Hall") made it synonymous with the Valley Girl dialectic of Angelinos.
The OED says the slang use is chiefly and originally US with quotations from 1982 to 2007, the earliest in the song "Jump to It", performed by Aretha Franklin's 1982 and written by Luther Vandross and Marcus Miller:
We have a lot of fun
Don't we, girl
Dishing out the dirt on everybody
And giving each other the 411
On who dropkicked who this week.
But I'm British and I'd never heard it before, and it wouldn't make sense with the equivalent to say you'd "give someone the 118" (nor with the older 192).
It is an Americanism and is outdated since nobody rings information / directory inquiries anymore.
It could also be misconstrued by today's digital generation since 411 is the http error code for "length required". So giving somebody the 411 might have a whole new meaning ;-)
Pronounced four-one-one, not four-eleven. Still in use a bit even if people no longer dial 411 for information.