Gizmo Project software is a communication tool that allows users to make free voice and video calls, send instant messages, and share files with other users of the software. It supports SIP-based calling and can be used to make calls to landline and mobile phones at low rates. The software also has a feature called "Call In" which allows users to receive calls on their computer from any phone number. Additionally, Gizmo Project offers conference call capabilities for up to 10 participants.