Method for controlling a telematics control unit (TCU), the telematics control unit (TCU) comprising a cellular modem hardware (CMH) and a processor and storage unit (PSU), the processor and storage unit (PSU) comprising a Processor (P) and a storage (S), - wherein a first exchange of commands and information (EX1.1, EX1.2, EX1.3) is executed on the processor and storage unit (PSU) between at least two telematics applications (TA1, TA2, TA3) and an application programming interface (API) of the processor and storage unit (PSU), - wherein a second exchange of commands and information (EX2.1, EX2.2, EX2.3) is executed on the processor and storage unit (PSU) between the application programming interface (API) and an hardware abstraction layer (HAL) of the processor and storage unit (PSU) and - wherein a third exchange of commands and information (EX3.1, EX3.2, EX3.3) is executed on the processor and storage unit (PSU) between the hardware abstraction layer (HAL) and a cellular modem hardware (CMH), wherein a cellular behavior manager (CBM) which is part of the hardware abstraction layer (HAL) is run on the processor and storage unit (PSU), - wherein the third exchange of commands and information (EX3.1, EX3.2, EX3.3) is controlled by the cellular behavior manager (CBM), - wherein access attempts of all telematics applications (TA1, TA2, TA3) to the cellular modem hardware (CMH) are recorded by the cellular behavior manager (CBM) via a chain of exchange commands and - wherein the cellular behavior manager (CBM) is configured such that it will monitor the telematics applications accessing the cellular modem hardware (CMH) and identify behavior that violates a set of rules (R) and permit or prohibit each access attempt accordingly. - wherein a first exchange of commands and information (EX1.1, EX1.2, EX1.3) is executed on the processor and storage unit (PSU) between at least two telematics applications (TA1, TA2, TA3) and an application programming interface (API) of the processor and storage unit (PSU), - wherein a second exchange of commands and information (EX2.1, EX2.2, EX2.3) is executed on the processor and storage unit (PSU) between the application programming interface (API) and an hardware abstraction layer (HAL) of the processor and storage unit (PSU) and - wherein a third exchange of commands and information (EX3.1, EX3.2, EX3.3) is executed on the processor and storage unit (PSU) between the hardware abstraction layer (HAL) and a cellular modem hardware (CMH), wherein a cellular behavior manager (CBM) which is part of the hardware abstraction layer (HAL) is run on the processor and storage unit (PSU), - wherein the third exchange of commands and information (EX3.1, EX3.2, EX3.3) is controlled by the cellular behavior manager (CBM), - wherein access attempts of all telematics applications (TA1, TA2, TA3) to the cellular modem hardware (CMH) are recorded by the cellular behavior manager (CBM) via a chain of exchange commands and - wherein the cellular behavior manager (CBM) is configured such that it will monitor the telematics applications accessing the cellular modem hardware (CMH) and identify behavior that violates a set of rules (R) and permit or prohibit each access attempt accordingly. <EOS>