Connectionless Transport Service (CLTS) is an Open System Interconnection(OSI) defined transport layer connectionless transport service with end-to-end addressing and error control.
CLTS services have no explicit route to the addressed end device through the network. The datagrams make up their own route. With connectionless methods, there is no guarantee that the data packets or datagrams will be delivered to the receiving station.
Connection Oriented Transport Services ( COTS) are in contrast to connectionless services.