SIPphone, the San Diego-based developer of the free Gizmo Project Internet calling and IM software, introduced an “All Calls Free” calling plan for businesses worldwide, providing significant savings for small to mid-sized companies who want to enjoy free calling between co-workers and/or remote offices. 
Using Gizmo Project as an office softphone, workers can place free PC-to-PC calls, as well as free calls to landlines and mobile phones of co-workers in 60 countries under the All Calls Free plan. The friends or co-workers must also sign up for the Gizmo plan. The United States, Brazil, and most European and Asian countries are included.
A variety of Asterisk PBXs, premium PBXs developed by such companies as Trixbox, SwitchVox, Epigy, webFones, and other SIP-based PBXs are supported by Gizmo Project. Workers can be called via their PBX or directly through the Gizmo network.
http://www.gizmoproject.com/business
