Kylie Jenner Leaked Number Off Limits

Kylie Jenner's phone number was shut down after Rob Kardashian leaked it -- and it won't be up for grabs again 'til next September ... TMZ has learned.

A rep for Verizon -- where Kylie had her phone plan -- tells us it's going beyond its usual policy of reassigning a disconnected number after 50 days. In this case, they're jumping straight to their max period ... one full year.

We broke the story ... Rob leaked Kylie's number Monday night after a baby shower mishap. As a shot to Kylie, who he apparently thought was to blame, he tweeted her digits for the world to see.

Verizon tells us they're quick to change a number if a customer complains about getting unwanted or harassing calls or texts. Kylie isn't getting any special treatment ... she just meets that criteria. Now they've moved to take it down and out of circulation for 12 months.

Meanwhile, you shouldn't waste your time trying to call Kylie ... her hotline won't bling.