"Block Caller ID" (*67) not working?

Hello Forum,

I made today a call to a 708 number and because I wanted to remain anonymous I dialed the number with the prefix *67. This call was in return of an unsolicited sales call that was made to me (better: my mailbox) earlier today. Usually I ignore such calls but in this case something tempted me to call back. I did not call back the number from which I got the call (708-300-xxxx) but the number that was given to me on my mailbox (708-833-xxxx).

After calling this number it took a very long time before somebody picked up (at least 30 rings) - and when then the conversation started I was shocked to hear that the person I was calling knew where I was calling from (a small town with just 10000 people) although I gave that person a completely wrong name.

How is it possible that this person knew where I was calling from? Could it be that *67 is not working with Voipo?

Greetings - wimax