Hi @Alessandro-Parmigiani ,
The RRC inactivity timer is set by the network and cannot be modified by the device. Its value is usually consistent within one network (there are exceptions, though!) but it is not necessarily identical across all network technologies (e.g. NB-IoT and LTE-M).
Note that for NB-IoT, the RRC inactivity timer may also have different values depending on the CE-Level in which the module is (CE0, 1 or 2).
In Germany, the timer is set to 10s for LTE-M and between 20s and 30s for NB-IoT depending on the area.
We are however reviewing those values at the moment and will most probably shorten the RRC inactivity timer for NB-IoT in the near future, especially for CE Level 0 and CE Level 1.
We will gladly inform you via this post whenever this change has been performed!
If your application however does not expect downlink data after sending an uplink message, we strongly recommend using the Release Assistance Indication on NB-IoT to bypass this RRC Inactivity period and immediatly switch to Idle mode (as mentioned by Stefan de Lange above).
RAI is supported across all DT NB-IoT networks, with some regional limitations within our Polish network.
This feature unfortunately isn’t yet available for LTE-M, but has been standardized by 3GPP. It is therefore likely to be implemented in the future both by module vendors and network providers.
Hope this can help!