06-28-2022, 09:05 AM
I have summarized the issue for the ModemManager folks as best I can, and will mark this issue solved.
The stored messages are not some sort of FIFO for the most recent X messages of any type as I initially suspected. They all appear to be SMS messages, though apparently not all SMS messages get stored in this manner.
A person can use AT+CPMS? to see the storage size and how much is used. A response like '+CPMS: "ME",35,99,"MT",35,99,"MT",35,99' would mean 35 of a maximum of 99 messages are currently stored. I think doing a AT+CMGD=,2 in a daily or even weekly cron will keep the system from getting clogged again until a proper solution is found. It seems like doing the purge too often risks interfering with normal modem operations.
The stored messages are not some sort of FIFO for the most recent X messages of any type as I initially suspected. They all appear to be SMS messages, though apparently not all SMS messages get stored in this manner.
A person can use AT+CPMS? to see the storage size and how much is used. A response like '+CPMS: "ME",35,99,"MT",35,99,"MT",35,99' would mean 35 of a maximum of 99 messages are currently stored. I think doing a AT+CMGD=,2 in a daily or even weekly cron will keep the system from getting clogged again until a proper solution is found. It seems like doing the purge too often risks interfering with normal modem operations.