GSM SIM800l not connected to the network

I have bought sim800l but netlight is blink fast 8 times and then off estimated 3 second. While i icheck CSOP : 0. Please tell me how to fix it.
Thanks very much

Your power supply is not able to supply the needed 2A current to the module. Make sure you have a good power supply which can deliver 2A current and you are using short thick wires to power the module.