Nokia on Push-to-talk: "Push to talk service users are typically engaged in some other activity than a telephone call, and they listen to the group traffic during their activity. A user can be contacted by the name, or he may occasionally want to say something to the group. Half-duplex traffic is ideal for such use cases. This simple, real-time direct communication serves the diverse needs of both business users and private consumers ranging from controlled team management to spontaneous sharing of experiences."