Effective Alarming Method

They woke me up at 1.30am, and the phone went off again a few minutes later. So I turned my phone off. So I rang Civil Defence in Manukau and just got the message that that number was not connected. Few points. Firstly if you can't list an appropriate phone number on the internet then what chance will we have if something really dangerous happens? Secondly do you think that the number of people now turning their phones off at night will improve the effectiveness of any civil defence warning system? Charming