[VoiceOps] STIR/SHAKEN Discussion: Will it help?

mike at astrocompanies.com mike at astrocompanies.com
Tue Dec 17 15:27:48 EST 2019

Hi Peter,

Good question.  First, if you're using Hooli, you'll have to migrate to
Pipernet sooner or later.  Their middle-out compression provides much better
call quality so it's worth the effort to migrate.

But to the issue you raised, the purpose of STIR/SHAKEN is not to block
robocalls per se, it is to provide an authentication chain so that you can
determine and contact the originating carrier regardless of the route the
call took to reach the terminating side.  This has been a big issue; many
VoIP companies hand off calls to large indifferent CLEC or IXCs who send
them everywhere but won't respond to the terminating carrier's fraud and
nuisance requests.

So, now we can see that the call was attested by Hooli, and if Hooli does
not cooperate with our fraud/nuisance investigations we are now authorized
to block traffic signed by Hooli.  That does fix the problem to a large

However, it's also worthy of note that this is not the main problem that
needs to be solved.  The main problem that needs to be solved is the case
where you are sending the call to Hooli originating from a number that is
assigned to our CLEC, which you don't have permission to use.  This does
solve that problem, because Hooli is only going to issue partial attestation
for that call since it's not their number.  So we can still contact Hooli
about it because they attested it and from that I can find them, but we or
our subscriber can also block calls with partial attestations if we/they
choose to.



Mike Ray, MBA, CNE, CTE
Astro Companies, LLC
11523 Palm Brush Trail #401
Lakewood Ranch, FL  34202
DIRECT: call or text 941 600-0207

-----Original Message-----
From: VoiceOps <voiceops-bounces at voiceops.org> On Behalf Of Peter Beckman
Sent: Tuesday, December 17, 2019 2:58 PM
To: VoiceOps <voiceops at voiceops.org>
Subject: [VoiceOps] STIR/SHAKEN Discussion: Will it help?

A few months ago I attended an FCC STIR/SHAKEN discussion in Washington DC.
They didn't get deep into the technical details but there were a bunch of
big carrier representatives there.

If you haven't followed STIR/SHAKEN, it's really just an additional SIP
header that contains cryptographically-signed information about the origin
point of the call.

You can verify the signature with publically published public keys so you
know whomever signed it is really them.

Here's a few resources if you want to learn more:


There are three levels to tell you how much you should trust the origin of
the call:

     1. Full -- The call came from the originating carrier's customer and is
         authorized to use the number

     2. Partial -- The call came from the originating carrier's customer but
         may or may not be authorized to use the number

     3. Gateway -- The carrier has authenticated from where it received the
         call, but cannot authenticate the call source (e.g., International
         Gateway call).

As an example, as will be many legit cases, a Verizon Wireless mobile
customer will place a call, which will route to Verizon, who will sign the
call using STIR/SHAKEN with Full Attestation and we can all "trust" the

But now we throw in VoIP.

I'm a small customer, Initech, of a larger carrier, Hooli. I don't sign my
calls, so I hand my calls to my larger carrier, Hooli. Hooli sees the call
from me (their customer) with a valid CallerID I'm authorized to use and so
Hooli signs the call with STIR/SHAKEN with Full Attestation.

Turns out the call was a robocall.

What changes? The only thing that changes is that the receiving party, say
Soylent Corp, knows that Hooli originated the call. Soylent is not Hooli's
customer, so how does Soylent complain to Hooli about the content of the

And as carriers, we are not legally responsible for the content of our
customer's calls.

How will Soylent accept 90% of Hooli's Fully Attested valid traffic but
avoid the 10% that is spam/robocalls that are ALSO Fully Attested?

How exactly does STIR/SHAKEN help fix the robocall and spam call problem?

Yes, I could block all of Hooli's calls where the attestation is Partial or
Gateway, but you run the risk of false positives, especially in the
International category, or just when Hooli isn't sure, like when I rent a
DID from Acme but do termination through Hooli -- Hooli doesn't know that I
am authorized to use that DID from Acme, even though I am, so Hooli has to
mark my call as Partial or Gateway.

I'm all for reducing annoying spam and robocalls, but I'm still not yet
convinced that STIR/SHAKEN is going to materially reduce them.

Let's discuss!

Peter Beckman                                                  Internet Guy
beckman at angryox.com                                 http://www.angryox.com/
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