The security mastercode is not to be used to get access to locked phones from anyone to change security code or get access to stolen mobile phones!!!
That mastercode will not work with phones 1100, 1110, 1600, 2100, 2300, 2600, 2650, also not for BB5 phones!
If you are sure to have never changed you your security code, try the Nokia default code: 12345!
Enter you IMEI (*#06#):