1) Viber

This app enables free calls and texts between its users worldwide using Wi-Fi and 3G. While the app works internationally, if you are personally abroad you could be asked to pay roaming charges, so check your calling plan’s conditions. Viber works on iPhone and the latest generations of iPod touch and iPad are partially supported.

2) Vonage Mobile

It offers free calls and texts to anyone who has the app worldwide, using Wi-Fi. It offers savings on international calls to users that don’t have the app. It claims to be 70 percent cheaper than most standard calling plans. Currently, Vonage supports iPhone, iPad and Android phones and tablets.

3) Fring

This app, besides free calls and texts to other Fring users worldwide, offers free group video and two-way video chat. It supports the major smartphones and tablets on any mobile operator and with any mobile internet connection.

4) WhatsApp

This app is to send free text and multimedia messages by using the same internet data plan that you use for email and web browsing. WhatsApp costs 62p and is available for iPhone, BlackBerry, Android, Windows Phone and Nokia.

5) Skype

The worldwide famous Skype started its service using computers, but it has now created many mobile apps which allow you to call almost any computer and any phone worldwide.Skype supports iPhone, iPod touch and iPad, Android, some Nokia and some Sony Ericsson handsets.