Re: [stir] Can canonical phone numbers survive SBCs and other middle boxes?

["Rosen, Brian" <[e-mail]>]

Yes, I'm asking if we can avoid using alternative headers.

I'll start a thread on call forward/follow-me.

I think presence of most prefixes would be pretty easy to deal with.  I would not expect to see the PBX prefixes (9-1-202-555-1212), because the downstream entities couldn't route if they were there.

Can anyone else on the list find examples where prefixes may confuse a canonicalization routine on From/To?

Brian
On Jun 7, 2013, at 1:58 PM, Hadriel Kaplan <[e-mail]> wrote:

> 
> On Jun 7, 2013, at 1:20 PM, "Rosen, Brian" <[e-mail]> wrote:
> 
>> After reading it, I am unclear if a canonicalized e.164 would make it through.  The reasons given seem to indicate they would.  They change domains, they change prefixes, but they don't seem to change the actual telephone number.
>> Can we come up with examples where a canonicalized e.164 would NOT pass end to end?
> 
> Depends on how you mean this - do you mean can we avoid putting a canonical version into a separate header, and instead keep it in the From/To?
> I don't know that we can really know the answer to that universally.
> 
> There are some times when the From/To username numbers are changed for reasons other than what I had in that old draft.  For example sometimes they're pre-pended with prefixes used for routing purposes, but the prefix is later removed before egressing the network.  That probably wouldn't matter so long as it got inserted after the signer and removed before the verifier, or the signer/verifier were aware of it.  Also the From number is sometimes replaced with a general company number, to hide the specific agent/attendant making a call; but that would hopefully happen before signing so it won't matter.  Sometimes the To is changed due to call forwarding/hunting/selection to be the new destination number, despite the RFCs that say otherwise.
> 
> -hadriel
>