Twitter users can now communicate on their mobiles for free using mobile VoIP provider fring 's mobile service.

Twitter, the online mini-messaging social networking service, has been integrated into the fring mobile VoIP service. Fring currently supports a wide range of popular VoIP and IM services. These include Skype , Google Talk and Windows Live Messenger (MSN).

Fring uses either mobile network or Wi-Fi data links to offer multiple communications options for users. There is no cost other than the data charge (free if the mobile user has a data plan subscription). VoIP voice calls, texts and instant messaging are supported. And users are able to tag stored contacts with icons for each type of service.

The downloadable fring application sits on the phone and users can view contacts' presence status online. They can manage their own presence for multiple services as well. On-screen icons show which services are currently online. Calls or messages can be sent by clicking on contacts in the fring contacts list (which can also be set to include the phone's address book).

Fring is currently available as a download for a selection of Nokia S60 smartphones. Fring has told Tech.co.uk it is panning to launch a version of the application for Windows Mobile devices shortly, with a Java J2ME version planned "before the end of 2007".