I usually get this when the phone has had power issues. I suspect the communication with the radio firmware gets out of sync and it takes awhile to sort itself out. Taking out the SIM and replacing it almost always fixes it for me. For those times when it hasn't a second try always does. I don't think it's a physical thing that increased pressure helps, I suspect it's just that you're taking out the SIM, and even whilst the phone is off, the radio controller is still running as long as there is reserve power in a capacitor or some such somewhere.