The present document defines the Terrestrial Trunked Radio (TETRA) system supporting Voice plus Data (V+D). It specifies the air interface, the interworking between TETRA systems and to other systems via gateways, the Terminal Equipment (TE) interface on the Mobile Station (MS), the connection of Line Stations (LSs) to the infrastructure, the security aspects in TETRA networks, the management services offered to the operator, the performance objectives, and the supplementary services that come in addition to the basic and teleservices.