Does Laird's MG100 support SMS?

As of 4Q-2023, we do not have any examples of sending SMS and the HL7800 driver in Zephyr does not have any SMS support. Though, it could be added on your own effort.  To see what it takes to add a new API, refer to https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/drivers/modem/hl7800.h.