The telecoms industry seems to be at an impasse. There’s a clear mandate for STIR/SHAKEN on VoIP calls, but the situation for TDM is a mess. The Tier 1s don’t want to offer VoIP tandem interconnect to independents – and they made clear in a recent filing with the FCC that they are unwilling to consider out-of-band STIR as a workaround.

For those of you who haven’t been paying close attention to this whole debacle – here’s the 30 second bunnies version:
- Robocalls are bad.
- In order to stop them we need first to stop caller ID spoofing.
- We can validate caller ID with STIR/SHAKEN.
- Which only works for VoIP, which is a problem for independents.
- The NTCA has told the FCC that we need VoIP interconnect (which the Tier 1s don’t seem inclined to offer any time soon).
- Congress passed the TRACED Act requiring STIR/SHAKEN to be implemented by June 30, 2021.
Out-of-Band STIR?
A few weeks ago I wrote about Out-of-Band STIR, a draft standard that could potentially provide a work-around to this issue – and which had been demonstrated in an NTCA webinar by TransNexus. At the time I wrote that in order for OOB STIR to work “we would ultimately need this to be adopted industry wide” – which seemed like a tall order, but “more likely than replacing all ISUP trunks with SIP in the next 15 months”.
Tier 1s say no
Well… maybe it’s an even taller order than I thought. Unbeknownst to me, the Tier 1 carriers really aren’t keen on Out-of-Band STIR. Earlier this month USTelecom, AT&T, CenturyLink, Frontier, Twilio, and Verizon filed an ex-parte notice with the FCC recording a meeting they held in which they…
expressed policy and technical concerns with nonstandards-based workarounds for certain traffic, including so called “Out-of-band STIR.” Richard Shockey [SIPForum] made clear that at this time there is no standard for Out-of-band STIR…
The Commission [FCC] should be skeptical of the viability of Out-of-band STIR as an alternative to STIR/SHAKEN for any calls (whether as an alternative solution for TDM or IP traffic) unless and until a standard is developed for such a solution.
USTelecom Representatives ex-parte notice, March 4, 2020
I don’t particularly buy the arguments made in the brief. It’s true OOB STIR is not yet an official standard. It’s a draft standard. So there’s a process that would need to be followed for it to become an official standard. That doesn’t mean it’s impossible. Not surprisingly TransNexus met with the FCC to rebut the technical arguments.
However, the merits of the argument aren’t my main point. The main point is that there’s strong opposition from the Tier 1 carriers to any attempt to use Out-of-Band STIR as an alternative solution.
The big question: is that opposition strong enough to block OOB STIR entirely? I don’t know.
What’s the best path forward?
We seem to be between a rock and a hard place.

- If the Tier 1s would make SIP interconnect available to ILECs and CLECs then we could all just use VoIP and STIR/SHAKEN. But that’s not going to happen any time soon.
- Out-of-Band STIR (if it became an official standard, and if it was adopted by the whole industry) could provide a work-around, but the Tier 1s apparently don’t like that plan either.
I was pleased to discover that Metaswitch make this very same point on page 6 of their own ex-parte filing with the FCC – so I’m not going crazy here. The impasse is real.
At this point I throw up my hands in despair. I’m a technical person, not a politician. I don’t pretend to know what the FCC will eventually do. They’re having meetings with a lot of different parties, who are trying to convince them of a variety of viewpoints.
My guess is that they’ll exempt TDM calls from the STIR/SHAKEN deadline, which removes the immediate pressure to solve that piece. And then…
Then they’re going to have to back a horse – either force everyone to support OOB STIR as an interim solution or else force all tandems to offer SIP interconnect.
The choice is not clear cut, and neither path is easy – but ultimately the FCC is going to have to choose. I hope they realize that.