I’ve run into the same problem: I have my phone connected to my personal accont, which I have been using to develop some apps, but I now figured it was more appropriate to create a company account and use that.
But I only have one phone number, and was not allowed to use that for the company account — and therefore I won’t be able to create apps for that account.
What puzzles me is that I found this article, where, at the bottom, Twitter says we should be allowed to use the same phone number for up to 10 accounts.
Now, this would be brilliant, and solve everything — however it does not seem to be the current reality.
So, am now wondering if it’s a bug or a feature …