In 1998 Yahoo launched its own IM service under the name of Pager, later top be called Yahoo Messenger. With its 22 million users Yahoo Messenger is an advertisement-supported IM service. Users are required to have a Yahoo ID, which also enables you to use other Yahoo services. Features of Yahoo Messenger include PC-to-Phone calling, PC-to-PC calling, plug-ins, voicemail, file sharing, webcams, and chat rooms, client customization, and avatars. It recently incorporated Yahoo Mail into its IM service. The current version is 9.0 and supports interoperability with Windows Live Messenger.