2FA [1] can be used in a variety of different computing environments and situations. You can use it for increasing authentication for accessing your network resources. You can also use it for reducing the likelihood of unauthorized access to your cloud computing environments and web-based systems. Further, two factor authentication can be applied to virtual private networks, extranets, and mobile devices, including cell phones, tablets, iPad, iPhones and smart phones.
Another use for 2FA is applying it to your VOIP phone system to regulate who is able to make telephone calls. Most companies have some method in place which limits employees from making long distance phone calls. Some companies even restrict local calls, because they are charged on a per-call basis. By using two factor authentication, employees will not be able to use your phone system without the proper authentication, which allows you to control your telephone expenses.
Links:
[1] http://www.digi-sign.com/products#category_136