Does *67 really block caller ID?

*67 - Block Caller ID (For Next Call Only)

I tried *67 today. No answer. But the recipent immediately returned my call. The recipient did not see my name, but was able to return the call. I did look at the call history on my phone just to double check *67 was dialed. *67 did not show on the VOIPO call history. I tried to replicate making a *67 call to my own cell; but I could not replicate. Is it possible that *67 does not always work?

The recipient could have used *69 to return the last call without caller ID. The phone company knows your number.

When you block CID, the number is still technically sent in the call headers, but it's flagged as "private". Occasionally there will be a receiving provider that refuses to honor the privacy flag and shows it.