Vonage launched a new app for the iPhone called Vonage Mobile that allows users to send free text messages and make free calls to other Vonage Mobile users. The app puts the company in direct competition with Skype and raises the stakes for carriers looking to protect their existing business model.

Vonage Mobile Screenshot

The app connects both iPhone users and Android device owners to one another. The company claims that calls made with the app use high definition audio and are higher quality than normal cell phone calls. In addition, it works over WiFi, 3G, and 4G (for 4G Android devices).

Another aspect of the app worth noting is that it doesn’t require users to set up a new login that they then have to share with other users. Instead, Vonage Mobile uses your existing mobile phone number as its internal ID.

When setting up your app, it sends a text to your iPhone (or Android device) with a verification code. Once you enter that code, the app uses your existing Address Book to identify other Vonage users, and incoming calls are identified according to your contacts, as you can see in the screenshot above.

Also, since Vonage is using its own servers to send out Push notifications in iOS, you don’t have to have the app running in the background to get notifications.

Vonage Mobile is a free app and doesn’t require users to be Vonage subscribers, but calls made to Vonage phone numbers (i.e. to Vonage subscribers) are also free. As a limited promotion, Vonage is also offering free calls to any phone in the U.S., Canada, or Puerto Rico.

The app is available from the App Store as a free download, but some people may experience App Store propagation issues that keeps Vonage Mobile from showing up immediately.