I want to switch SIM card "hot",
i use at_command to check SIM card:
"AT+CPIN?\r"
i feel:
modulSIM900 can automatic to understand:
if ModulSIM has got SIM Card ("respond : +CPIN: READY") and ModulSIM work normally (call, send SMS...).
if ModulSIM hasn't got SIM Card ("respond : +CPIN:NOT READY"") and ModulSIM don't work normally(don't call, send SMS..).
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Almost case is OK, no problem.
But sometime, there is SIM Card in ModulSIM and "respond : +CPIN: READY" -> ModulSIM don't work normally(don't call, send SMS..).
I try to by way: send atcomand: "AT+CFUN=1,1\r" and delay 2 second ( i try 1second, but not ok) -> ModulSIM work normally.
Can you help me explain this problem, i don't want to delay time > 1s. This is correct way to switch SIM "hot"?, can you show me the another way?