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: https://www.bandwidth.com/glossary/stir-shaken/ https://www.fcc.gov/call-authentication https://en.wikipedia.org/wiki/STIR/SHAKEN https://www.home.neustar/stir-shaken-resource-hub 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 call. 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 call? 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! Beckman --------------------------------------------------------------------------- Peter Beckman Internet Guy beckman at angryox.com http://www.angryox.com/ ---------------------------------------------------------------------------