When did Teletype become obsolete?

[FDRfan1985]

^^^

[dead0man]

Are you asking about the typewriter things that worked as computer monitor?  If yes, the answer is when computer monitors became cheaper than the typewriter things/+cost of paper. 

I used one from '97-99 on a Vax computer.  When I first got in the shop I was tasked with running some reports on one of them.  I did something wrong and the thing just kept printing....and printing....and printing.  I didn't know about ctrl-C yet.  I called down to the shop to ask for help and they laughed and laughed.  Then told me about Ctrl-C.