Where can you a doc explaining the meaning of SetCallerPres() values (see )?
What does this Passed Screen, Failed Screen, … is all about ?
Said differently, what do you loose when normalizing all values starting with allowed or prohib to allowed or prohib, respectively ?
They come from ISDN, so will be documented in the ITU-T documents.
Passed screen means that the provider recognized the caller ID as one that was valid for the immediate source of the call. Failed screen means that the numbers is being passed, but definitely doesn’t belong to the source. Prohibitted means that number must not be displayed.
Here, regulation bodies stress that telephony providers must check CallerID (as received in either in From, Diversion or History-Info header) is owned by caller.
In case CallerID is not owned, outbound call must be refused by originating ITSP.
(For inbound calls, I don’t what should be done).
So a compliant ITSP should only send calls with prohib_passed_screen or allowed_passed_screen, right ?
How do you pass this “passed_screen” semantic to the next ITSP ? With a simple P-Asserted-Identity ?