[VoiceOps] SUBSCRIBE/NOTIFY method for CNAM querying

Ryan Delgrosso ryandelgrosso at gmail.com
Mon Oct 30 16:25:13 EDT 2017

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

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