The Boron 2G/3G and Boron LTE can use either the built-in MFF2 embedded Particle SIM card or an external nano SIM card in the SIM card connector. The active SIM card setting is stored in non-volatile memory and only needs to be set once. The setting will be preserved across reset, power down, and firmware upgrades.

All other cellular devices either have only one type of SIM (either MFF2 or 4FF), but not both, and do not support Cellular.setActiveSim().

For Boron LTE modules, a special command needs to be given to the cell radio after setting setActiveSim. If this command is not given, the device may end up blinking green, and the device does not connect to cloud. Please refer to this support article if you are switching SIM cards with Boron LTE.


void setup() {
    // Choose one of these:

void loop() {