I have a SIM900 R11.0 module and its Evaluation Board EVB_V1.01
First I have bought modules, I could connect network and send SMS. But I could not make FTP connection because of firmware version.
So updated the firmware to 1137B12SIM900M64_ST
But now, I could not even connect to network.
SIM connection is ok.
Signal quality is around 27
Phone functionality is ok.
IMEI registration is ok.
But CREG? gives 1,3 means, trying to connect network but registration denied.
What should I do?