This week BlackBerry (NYSE:BB) CEO John Chen released a statement to CNBC reiterating for the second time in several weeks that the company has a strong outlook and that it's here to stay.

Source: BlackBerry.

Chen spoke about BlackBerry's approval by the Department of Defense to use its devices with the highest level of security -- called Authority to Operate. In the statement, Chen said BlackBerry is the only company to have its devices approved for usage by the Department of Defense. While the exclusivity of the Authority to Operate-level designation is true, government-issued Apple (NASDAQ:AAPL) iOS devices were approved to run on certain DoD networks earlier this year.

There's no denying that in the past the DoD has by far preferred BlackBerry over any other device. This past May the agency had 470,000 BlackBerrys compared to 41,000 iOS devices and about 8,700 Android devices. BlackBerry is holding on to a lead it gained while iOS and Android were either nonexistent or in their early stages, but that doesn't mean the two OSes aren't making huge strides against BlackBerry in the government sector.

Earlier this year, a Defense Information Systems Agency statement said Apple's iOS 6 devices "are approved for use when connecting to DOD networks within current mobility pilots or the future mobile device management framework" and that the approval is "a major stride in building a multi-vendor environment, supporting a diverse selection of devices and operating systems" (emphasis added). Apparently, the DoD is open to other devices that don't bear the BlackBerry name.

So, while the company can brag for now that it's received the top security designation, it doesn't mean that it holds a monopoly on all DoD network approval in the future or that other government agencies can't use anyone else but BlackBerry. 

So far, the Federal Air Marshal Service, the Coast Guard, and the Bureau of Alcohol, Tobacco, Firearms and Explosives have not only approved iPhone usage but switched entirely from BlackBerry devices. And in 2012, the Department of Homeland Security also switched more than 17,000 employees from BlackBerrys to iPhones for the Immigration and Customs Enforcement division.

The U.S. government isn't the only one making the switch, either. The U.K. government has also approved iPhones for government employees.

BlackBerry may still have the lead in some enterprise sectors and government agencies, but there's clearly a move to add iOS and Android to the lineup, if not an all-out switch away from BlackBerry in some instances. Chen said in his statement that because of its recent approval, BlackBerry "cannot just be replaced" by the government. While Authority to Operate may give BlackBerry an advantage in certain parts of the Department of Defense, it's evident that government agencies are indeed switching -- and BlackBerry is being replaced.