Users are registered and identified through a cellular telephone number, although the service is accessible on desktop platforms without needing mobile connectivity. Viber, or Rakuten Viber, is a cross-platform voice over IP (VoIP) and instant messaging (IM) software application owned by Japanese multinational company Rakuten, provided as freeware for the Google Android, iOS, Microsoft Windows, Apple macOS and Linux platforms. It may require cleanup to comply with Wikipedia's content policies, particularly neutral point of view. A major contributor to this article appears to have a close connection with its subject.