If someone used *69 to block their number, they don't WANT you to see it, and it will be blocked on your call details as well. If you absolutely must see the number, then you can use a service like TrapCall to reveal it (in some cases) at the time of the call. There is a fee though, and not all numbers will be viewable.
They also won't show up on the bill details - the whole point of a block is so the number is not shown.
Umm ... *69 does not block numbers.
*69 is what you call to call back the last number that called you.
Ummm, yep, right you are! *67 is the one that blocks your number? I never use it...