Brian West wrote:

It will always contain the number.  Its the far ends responsibility to  
honor the privacy flags.  The same happens on a PRI as far as I have  
seen.  Nobody should have the ability to withhold that info from your  
"switch".

That's not quite the case. In the good old world, there was generally a fairly clear
distinction between users and carriers. Caller ID would be passed between carriers
with the privacy flags set or not as required, but, if it had been withheld by a caller,
would not then be delivered to the end user. Otherwise you're essentially giving it
to the end user and asking them not to peek, which isn't terribly secure.

Nowadays, if I want to withhold my CLI, I don't send anything. That works pretty
well. Don't put junk in - I know that I can't call various destinations over BT if I
use something bogus (like na, or thiscliisaloadofoldbollocks[1]); I get a 403 Forbidden
back.

--Dave

[1] "bollocks" was once defined on Wikipedia as "the Swiss army knife of andrological
profanities" - unfortunately, like most excellent stuff on the word's most comprehensive
Star Trek factsheet encyclopedia anyone can ruin, that particular gem's been edited out.
http://en.wikipedia.org/wiki/Bollocks is still worth a read, though.