asterisk users - Mar 2006 - can't call some numbers/providers , ani code missing in sip header (found the problem, not the solution)

With the help of one of the providers we terminate on, I've found the 
source of the problem of getting busy even when the called isn't really 
busy in the absence of ANI codes in sip headers generated by asterisk.

If I put a NoOp(${CALLINGANI2}) in the dialplan before the dial I can 
see it holds the value '0', but seems that value won't find the way
to
the sip header.

Is this an error for asterisk to not put the code or a misconfiguration 
of the remote switches to drop calls without it ?
(Have I to open a bug or to request a feature ?)