From the Dial Plan

About three years ago, we launched Trunking Version 2.2 to make maintenance on our core voice network invisible to customers. Most partners have already moved. If you still have trunks on Version 1.0, this article explains why it matters and how to fix it.

Any trunk labeled V1.0 should be migrated. New trunks default to V2.2 automatically, so there’s nothing to change when you create one.

Our carrier switches are the backbone of the Wiretap voice network. Because they do the heavy lifting, they also need the most maintenance, both planned and unplanned.

Version 1.0 connects your PBX directly to one specific carrier switch. When that switch goes offline, your calls stop until your PBX re-registers with a switch that’s still up.

Version 2.2 puts a layer of geographically diverse session border controllers (SBCs) between your PBX and our carrier switches. Your PBX talks only to the SBC clusters, which wrap around the entire carrier switch network. When a switch goes down, the SBCs simply route your calls around it. The SBC layer is lightweight and extremely stable, so it rarely needs maintenance of its own.

We will send advance notice before any work begins. Even so, notice can’t prevent an outage on Version 1.0: if your trunk is pinned to a switch we take offline, your calls are affected. Version 2.2 trunks will keep working through the entire window.

There’s a second reason to move. We have reduced the geographic redundancy of the Version 1.0 network, so Version 1.0 trunks now have fewer fallback paths than they once did. Migrating to Version 2.2 restores that redundancy and protects you from future maintenance, too.

Newer customers are already covered. Version 1.0 has not been offered in the Wiretap Portal for many months, so any trunk created recently is on Version 2.2 by default.

Mostly, but the mechanism isn’t evil. The intent is. Plenty of legitimate setups show a number that isn’t the line the call physically left from:

• A doctor’s office calls patients from a cell phone, and the patient sees the practice’s main line.
• A call center shows one callback number across hundreds of agents.
• A business puts its toll-free number on every outbound call so customers always know who is calling and where to call back.

Without that flexibility, callbacks would land on a random mobile or a trunk nobody answers. U.S. law targets spoofing done with intent to defraud or cause harm, not the ability to present a number you’re entitled to use. That’s the whole reason attestation has levels instead of a simple yes or no: the carrier’s job is to confirm that the customer has the right to the number.

When attestation punishes the good guys

Here’s a real-world example of where the levels get awkward. Say a business forwards its main line to the owner’s cell phone after hours. A customer calls in, and the call gets forwarded out to the cell, still carrying the customer’s number as the caller ID.

We know our customer. What we can’t do is confirm that our customer has any right to use that caller’s number, because it belongs to someone else. So that forwarded leg can’t earn more than a B. It’s a completely legitimate call, and it comes out with a lower grade anyway.

That’s the negative side of attestation. The grade says how much the carrier can verify, not how trustworthy the call is. Honest traffic can end up with a B while a scammer running a SIM box collects an A.

Here’s the catch: a signature proves who signed the call, not that the call is honest. And scammers read the same standards we do.

Signed doesn’t mean clean. According to TNS’s 2026 robocall report, SIM boxing lets scammers originate fraudulent traffic inside a carrier’s own trusted network. The calls can pick up A-level attestation and sail past the checks designed to catch them.

Adoption is uneven. TNS’s half-year report, as summarized by BriefGlance, puts signed inter-carrier traffic at roughly 85% for the top seven U.S. providers but only about 20% for smaller ones. It also found that 17% of confirmed spoofed calls carried A attestation. When roughly one in six bad calls looks like the best kind of call, a green checkmark stops being a safe bet.

Regulators are catching up. On April 29, 2026, the FCC issued a further notice of proposed rulemaking on enhancing STIR/SHAKEN. It proposes to codify the attestation levels and their criteria, close the “attestation knowledge gap,” and prohibit improper attestations outright.

None of this means STIR/SHAKEN failed. TNS itself describes it as a valuable foundation that was never meant to be a silver bullet. It means the signal needs backup: consistent attestation practices, better know-your-customer checks, and analytics that look at how a call behaves, not just how it’s signed.

Then the tool became the bait

When scams get good enough, the next target is the people chasing them.

The Industry Traceback Group (ITG) is the organization the FCC has designated to coordinate private-sector tracing of illegal calls. Created by USTelecom in 2015, it works with providers across wireline, wireless, VoIP, and cable to follow suspect calls back to their source. When the ITG asks a provider about a call, the provider is expected to respond, and quickly.

That’s exactly what makes the ITG a good thing to impersonate. The ITG has posted a notice on its website saying it is aware of fraudulent emails impersonating it and is investigating. Its guidance is blunt: every official traceback request comes from the tracebacks.org domain, and anything claiming to be the ITG from a different domain should be treated as malicious.

Think about what a legitimate traceback involves. One provider’s account describes an emailed link, a portal account, and forms asking about the call, including whether it was signed with STIR/SHAKEN and what the SHAKEN header looked like. That’s a pile of operational detail about your network and your customers. Handing it to a lookalike would be a gift.

A note on what we know: the ITG’s notice confirms the fraudulent emails but doesn’t spell out who was targeted or what the senders were after, and we haven’t seen a public breakdown. We’ll update this post if more details come out.

We have skin in this game, so here’s where we stand.

We sign the calls. Wiretap Telecom has been signing calls on behalf of our customers since the FCC’s STIR/SHAKEN mandate took effect. We sign all of the calls on our network, and customers we’ve approved can also sign their own calls. Once Wiretap Telecom has reviewed and approved a customer’s RMD status, they can sign their own calls, and it’s all handled through the Wiretap Telecom portal.

We’re in the Robocall Mitigation Database. Every provider has to file with the FCC’s Robocall Mitigation Database (RMD), and the FCC has been removing providers that don’t comply. Our RMD number is RMD0001594, and you can look us up in the database yourself.

We answer the ITG. We have always been compliant, and we have always reported information to the Industry Traceback Group when asked, within the 24-hour reporting requirement. That’s also one reason a fake request is easy for us to spot: we know what a real one looks like.