ISO 13183:2012 specifies the architectural communications framework of intelligent transport systems (ITS) for the family of communications access for land mobiles (CALM) related International Standards. The architecture is described in an abstract way with several graphical views and examples. The graphical representations partly follow the ISO open systems interconnection (OSI) principles.

In addition to the requirements specified within ISO 13183:2012, a number of notes and examples are provided to illustrate the CALM concept.