I am very new to the SIM domain (and new to cell phones too!). I want to check if a SIM800C evaluation module with a recently purchased SIM card to a local provider works well, and I’m not sure of anything.
The communication between the RPi0 and the module is OK, and I decided to power the SIM module with an old PC power supply, so I do not have to worry about the 2 amps of maximum current .
I have written software that places the SIM module in a known state when the system is restarted or powered up, it seems to work well. Then I run “miniterm.py” to send commands and requests to the module.
My first question is: how can I be sure that the module is connected to the radio network ? (note: in the following texte, the character ’⏎’ means the two characters “\ r \ n” in that order, while ’↵’ means “\ r” only, with ’\ r’ = 0x0D, 13, and ’\ n ’= 0x0A, 10, .
The most surprising is that every time I start the module, the LED of the network LED always flashes the same way (10 flashes in 8~ seconds), the antenna being connected or not !
The module has a strange behavior. For example, using miniterm program, the command:
⏎+CBAND: PCS_MODE, ALL_BAND⏎
at the first query. I do not feel especially bad with that !
When I try to modify this parameter, the answer is of type
except for PGSM_MODE which gives
⏎+CME ERROR: operation not authorized⏎
. For all these commands, if I add “,ALL_BAND” to the first parameter, the answer is
⏎+CME ERROR: unauthorized operation⏎
. It looks like that the ALL_BAND option is always added, a sort of default setting. But in that case, why did the module answered "⏎+CBAND: PCS_MODE, ALL_BAND?⏎ at the very first query ?
I am really wondering if the ME part of the SIM is well working. Could someone tell me, please, how can I check that.
Thank you for the attention you paid to this topic.