Inmarsat-C is intended for low speed data communication. The speed is of the order of 600 bit / s. The messages have a maximum size of 32 kb. Due to the low speed, a small omnidirectional antenna is sufficient.
Inmarsat C uses the following frequencies:
1626.5-1645.5 MHz (transmit)
1530.0-1545.0 MHz (receive)
The terminals can be easily integrated with a positioning system, such as GPS, for fleet management, for example. Terminals can be polled automatically, sending up to 32 bytes of information. Inmarsat-C also offers the option of a group call, in which information is sent to all terminals in a certain area or all terminals from a certain group.