Communications technology puts the S (for 'system') in ITS. Ever-increasing availability of communications, together with inexpensive, and miniaturized computing technology, have combined in recent years to create the technological momentum that launched the ITS development we see today.
ITS comprises 30 different user services. Some of these do not require communications, but most do. The National Architecture for ITS provides us with the definitive assessment of what types of linkages are needed for each user service to operate fully as intended.