Yes, you can still use it, you just have to set it up a little differently. You will need to get an "application specific password" or ASP when you set-up your verified devices. Go to the "authorizing applications & sites" page under Google Account settings. The set-up page for 2-step authentication will offer the option of generating an ASP and once you select it and generate an ASP you can enter it into the window that will pop up on your phone. Enter it, and you are good to go. Once you go through this process, the older phone will work just fine with 2-step verification.  I also suggest installing Google Authenticator (free from Google Play)  on your mobile device once you have completed initial set-up. Hope this helps. Google also has a page that walks you through the process.