Sources speaking to 9to5Mac claim that Verizon Wireless has blocked its employees from taking vacation days between Wednesday, Sept. 18 and Sunday, Sept. 22. There's no concrete evidence to show that Apple is planning to launch its new iPhones during that period, but the company followed a similar pattern with the launch of the iPhone 5 last year, announcing the new device on Sept. 12 and then releasing it on Sept. 21. 

In addition to this latest report on Verizon, two other leaks have recently suggested that AT&T and T-Mobile are planning similar blackouts. BGR claims to have been told by "multiple sources" that AT&T has blocked out vacation days for the second half of September. Meanwhile, our pals at TmoNews have heard that T-Mobile has set a vacation blackout from Friday, Sept. 20 through Sunday, Sept. 22.

We won't know Apple's iPhone launch plans until its executives take the stage on Sept. 10 and reveal the information themselves, but Friday, Sept. 20 sure is starting to look like a solid release day candidate. As I mentioned before, Apple announced the iPhone 5 on Sept. 12 and then launched it on Friday, Sept. 21, and in 2011 it announced the iPhone 4S on Oct. 4 and launched the device on Friday, Oct. 14.

In other iPhone news, 9to5Mac has learned that supplies of the 32GB and 64GB iPhone 5 models have become constrained at Verizon Wireless, while the 16GB variant is still in regular supply. The site suggests that with Apple rumored to be bumping the iPhone's maximum capacity up to 128GB this year, we could also see the a base-level iPhone 5 stick around with 16GB of storage rather than the 8GB found in previous entry-level models. That'd certainly be a nice upgrade for consumers that would opt for the base model, as 8GB can begin to feel cramped after loading some music, photos and apps onto a device. 

Via 9to5Mac, BGR, TmoNews