The first place i recall seeing this flow was Broadsoft. It was the sole method you could perform CNAM dips as far back as I can recall which was R13. To carbon date that, other softswitches which would have been contemporaries to Broadsoft in ~2005 when that was state of the art were Sylantro (no such support) and Metaswitch (only SS7 support at the time). My guess is Broadsoft may have defined a de-facto standard by implementing an esoteric mechanism, and forcing their large subset of customers to require it so all the providers supported it and viola a standard is born. If this is true its unlikely you will find any ratified standard. Maybe someone with deeper historical roots than I could shed some light on this, though FWIW this flow has a decidedly broadsoftian feel to it. On 10/30/2017 12:12 PM, Alex Balashov wrote:
Thanks Carlos.
But to clarify my question:
There is clearly is *some* kind of standard out there, as indicated by the number of (big) vendors who implement it in an agreed-upon way.
So, what I'm trying to figure out is what that standard is and where it's defined.
The Neustar documentation contains obvious cut-and-paste from an ABNF spec:
calling-name-request = callee CRLF [ called CRLF ] callee =?Calling-Party? HCOLON addr-spec called =?Called-Party? HCOLON addr-spec addr-spec =SIP URI / SIPS URI / TEL URI
And it does not seem thematically consistent with the general tenor of that document to suddenly break out some ABNF on their own accord. So, this syntax spec comes from *somewhere*, though no citations revealing its provenance are provided.
The same kind of thing is true in all other docs on this topic from other major vendors. None of them reference anything non-generic (e.g. RFC 3265).
So, what's the standard? Is it the Verizon patent? If so, why don't they any vendor docs refer to it by name?
-- Alex