Sorry, I ment the GREEN LED (D1) should blink, important, with an interval of approx. 3 seconds. If it blinks faster, a locked SIM card may be the issue.
The RED LED should be on.
I misinterpreted the word “locked”. If you have an unlocked SIM, meaning you can use it on any network, this is a good start. But, you have to remove the security from the SIM card. It’s easy to test, put it in a mobile, start the mobile, and when the mobile does not ask for a PIN code, it’s OK. When it asks for a PIN code, it’s locked. Normally you can remove this then via the security functions of your mobile phone (cfr. for exaple forum.cyanogenmod.com/topic/7805 … ndroid-os/ ).