is not joseki. There are a lot of ways to play and each path depends on the global situation of the board.
is almost unavoidable. If white would hane from the lower side than black can move to the center in sente as seen in the following diagram. White gets a rather flat position.
Next white must be aware that black can answer white's atari with a counter atari. If white does not like the result of the following diagram, then white should skip the atari. Instead of the atari white can simply catch the single black stone if he is satisfied with that. On the other hand the white atari on the outside emphasizes the importance of the lower left corner.
Also notice the possibilities of ladders for black:
For instance when the lower side is not interesting, black also has the option to skip the crosscut.