Vonage has launched a voice over IP (VoIP) application that allows users to call each other from their Facebook page without the need for either caller to disclose their phone number. The Vonage Mobile Facebook application can be used on either an Apple iPhone or a Google Android smartphone and costs nothing to download and install.

Vonage is a small business and consumer VoIP communications company with a customer base of more than 2.4 million users, primarily in the US, Canada and the UK. Its software works in a similar manner to the better-known Skype service. The Vonage for Facebook application is non-proprietary, so users do not have to subscribe to one VoIP service and only be able to make free calls to other users of the same service. Calls are made over 3G or Wi-Fi depending on the connections available.

The Vonage Mobile for Facebook app is being launched in 82 countries with all but 10 (those where 3G coverage is very limited) offering 3G as well as Wi-Fi calling.

Vonage believes there's a demand for a communication method that does not disclose people's personal phone numbers and yet draws on the 55 million-strong the membership of Facebook social network. People are increasingly connected but don't want to give away more of their privacy in order to communicate with their friends in the way they want, Vonage reasons.

The Vonage for Facebook application shows you which of your Facebook friends can be called for free. Having downloaded the application from the App Store or the Android Marketplace you are prompted to sign in your Facebook and to allow Vonage to find your contacts there. You can specify whether or not to allow push notifications on your phone - useful if you want to be sure you're not going to miss incoming calls from Facebook friends.

Incoming calls launch the Vonage application so you can chat or dismiss the call depending on whether it's convenient to chat. This could be an important factor since in this first iteration there's no mechanism for indicating to the caller than they may be about to rouse their less-than-pleased chums the other side of the world at 4am.

Vonage acknowledges this and status availability for call recipients will be addressed.

In the demonstration to Macworld and PC Advisor last week we found some significant lag when trying to conduct a conversation using the service. However, we were initially trying it out over a very poor Wi-Fi connection. When we tried again over a more dependable Wi-Fi network the latency issues largely disappeared and we were able to chat in a fairly seamless manner. Calls didn't seem to suffer from being staccato and the other person could be heard clearly without any noticeable line interference. However, our trial was over the same network within the same office setup rather than conducted over a long distance.

Vonage says its aim is to create "communities" that are connected and can communicate. Expect similar calling services to appear for Twitter and other social media services soon. Facebook chat is already supported with video calling a possible future addition. Given Vonage's strong business credentials, we also expect to see LinkedIn and other business community offerings to appear. Vonage says voicemail-to-text is among its plans, for instance.

Vonage for iPhone works with all versions of the Apple iPhone and with Android handsets that use the 1.5 and newer versions of the OS. It is optimised for use with Android 2.0 and later. The codec Vonage uses was not disclosed but was developed in Israel.