[asterisk-users] Automatic Number Identification and anonymous calls

[Olivier]

Hi,

This morning I called an analog line from a cell phone.

For the first call, I made a standard call and could both read my CID
and ANI in my Asterisk console.
For the second call, I choosed to hide my ID and, to my surprise, I
read that my CID and ANI were both empty.

I always thought that ANI (Automatic Number Identification) could not
directly be set or changed by end users.
In this experiment, it seems that if an end user calls anonymously,
the ANI is also hidden to the receiving party.

Is this standard practice ?
Does it depends on the telco networks the call is passing through ?
Thoughts ?

Regards