Communications access for mobile land (CALM)  is an initiative by the ISO TC 204 / Working Group 16 to define a set of wireless communication protocols and air for interfaces has variety of multiple scenarios spanning communication modes of communication and multiple methods of transmission In Intelligent Transportation System (ITS). The CALM architecture is based on an IPv6 convergence layer that decouples applications from the communication infrastructure. A standardized set of inter-protocol protocols is used for short, medium and long-range communications, using multiple multipoint (mesh) transfer.
Since 2007 CALM stands for Communication Mobile, before that year, CALM stood for Communications, Air-interface, Long and Medium range.
CALM enables the following communication modes:
- Vehicle-to-Infrastructure (V2I): communication initiated by either roadside or vehicle (eg petrol forecourt or toll booth)
- Vehicle-to-Vehicle (V2V): MANET’s / VANET’s.
- Infrastructure-to-Infrastructure (I2I): point-to-point
Methods of transmission used by CALM may be based on one or more of the following communication media:
- GSM (2G, 3G cellular telephone communication technology)
- DSRC 5.8-5.9 GHz (legacy systems)
- Various evolutions of the IEEE 802.11 standard including WAVE (IEEE P1609.3 / D23), M5 (ISO 21215)
- WiMAX , IEEE 802.16e
- MM-wave (63 GHz)
The CALM architecture provides an abstraction layer for vehicle applications, managing communication for multiple concurrent sessions spanning all communications modes, and all methods of transmission.
Applications for CALM are likely to include in-vehicle internet access, dynamic navigation, safety warnings, collision avoidance, and ad hoc networks linking multiple vehicles.
The CALM architecture protects critical communication in the vehicle using a firewall controlled by the vehicle. Parental controls are also considered as a component of the architecture.
The CALM standard is still work in progress. Therefore, large scale implementations of the standard do not exist. CVIS  is a project funded by the EC in the sixth framework program ( FP6 ). The aim of the project is to develop and implement a communication infrastructure based on the CALM architecture. CVIS will implement CALM M5 , 2G / 3G and IR as communication media. The implementation will be tested at several tests across Europe with a wide range of ITS applications.
- Http://www.safespot-eu.org/ SAFESPOT EU Integrated Project on Cooperative Vehicular Systems for Road Safety
- Http://hal.inria.fr/inria-00419466/en/ Architecture for Vehicle-Infrastructure Communication
- Jump up^ http://www.isotc204wg16.org/concept
- Jump up^ http://www.cvisproject.org/CVIS project