I am using SIM800 powered by 5V/2A wall adapter with LM2596 to get 4.0V that the SIM800 needs. I added 1000u cap, just in case. Its connected to PC using USB to Serial.
The module has never been able to register with the network so far.
AT+CREG? always returns +CREG: 0,0.
Trying to register by sequence of of AT+CFUN=0 and AT+CFUN=1 always returns +CPIN: NOT INSERTED.
I ve used the supplied antenna as well as external antenna. AT+CSQ is always above 27.
I ve tried 3 sims, each of which work fine on a phone but never worked on SIM800
Can somebody point me to whats wrong?
Thanks and Regards,