There is no evidence yet to support that the 830 has been discontinued. Lumia social media accounts are still promoting it, and the rumor making the rounds are all citing the same "anonymous Microsoft employee" that's being vague and can barely speak proper English.
Yes, it true that there is no proof to support the news. But it is also a fact that Lumia 830 is no longer available with both local and online retailers in India. If it is available then only in Black. The White one is rarely available, too rarely. I saw it yesterday listed on a website. And today it is gone! The orange and green ones are seriously no longer in stock. Not even with Nokia showrooms. There is only one listing of Green one on eBay India but that too is IMPORTED with just a 3-months seller warranty only for software-related issues.
I have personally tried contacting more than 30 potential as well as small retailers to no avail. Potential stores being the large mobile showrooms.
By these observations anyone can conclude that Lumia 830 has indeed vanished from the market.
I assume that you may have read a post by both
NPU and
WMPU (Sourced to NPU) which states that MSFT might have stopped the production of the phone in India. If there are any more available then they are the last ones to do so. Once they are gone, they won't be replenished.