Belledonne Communications is a company specializing in VoIP (Voice over Internet Protocol) and instant messaging solutions. They are renowned for their development of Linphone, an open-source, cross-platform software that allows for voice and video communication over the internet. Linphone supports various platforms, including mobile and desktop environments, and is known for its high level of interoperability and security. Belledonne Communications provides solutions tailored to individual and enterprise needs, focusing on seamless and secure communications.