ISO 21212:2008确定第二代（2G）蜂窝网络和2G系统（例如，使用WAP和I-Mode类型协议）的空中接口符合CALM，即2G系统并入CALM系统之前必须满足的要求。特别是，它规定了2G系统应包括的协议和参数，以在其环境中支持长时间、长距离、高数据速率的无线通信链路，其中异构切换或媒体独立切换（MIH）是维持链路所必需的，或者是由媒体选择策略确定的理想情况。 ISO 21212:2008为使用第二代蜂窝通信的ITS部门的远程、中速无线通信提供了协议和参数。 在可行的情况下，ISO 21212:2008是通过参考合适的现有标准制定的，通过选择采用。 提供了所需的区域差异。 具体而言，对于ISO 21212:2008，参考采用了各种国际和国家标准定义的现有2G系统。 ISO 21212:2008中不包括特定于应用程序的上层，但将由应用程序标准（可能不是特定于技术）驱动。

ISO 21212:2008 determines the air interface for second generation (2G) cellular networks and 2G systems (e.g. using WAP and I-Mode type protocols) to be compliant to CALM, i.e., requirements that must be met before a 2G system can be incorporated into a CALM system. In particular, it specifies protocols and parameters that 2G systems shall include to support prolonged, long-range, high data rate wireless communication links in ITS environments where heterogeneous handovers or media independent handovers (MIH) are either necessary to maintain the link, or desirable as determined by media selection policies. ISO 21212:2008 provides protocols and parameters for long range, medium speed wireless communications in the ITS sector using second generation cellular communications. Wherever practicable, ISO 21212:2008 has been developed by reference to suitable extant standards, adopted by selection. Required regional variations are provided. Specifically, for ISO 21212:2008, extant 2G systems, as defined by various international and national standards, are adopted by reference. Application-specific upper layers are not included in ISO 21212:2008, but will be driven by application standards (which may not be technology specific).