Since, you are installing an app that does not appear in the Play store, try this. Go into Settings> Security> Unknown sources and check the box, and try to download the app again.
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I already have unknown sources allowed. The problem is that the systems, both Vlingo's website and Google Play think my phone is running android v1.x. Even with unknown sources allowed, Google Play won't even let me see the Vlingo app in a search, it filters it out.