1) you are not a spy.
2) you are not important.
3) you have a choice, abide by the rules or do not enter. If you do not want to fill in your mobile number don't enter the comp.
4) This is really simples and I should not have to bother writing this to explain the frighteningly obvious to you.
5) it is merely a mobile phone number, one should use the word 'shame' when discussing important things (children starving, people dying of treatable illnesses etc.) not totally trivial rubbish.