Learn more about this issue and potential call authentication solutions below.
STIR/SHAKEN for Non-IP Phone Networks
While STIR/SHAKEN has reduced the number of illegal robocallers reaching victims over IP-based networks, these bad actors can still exploit non-IP phone networks. The FCC launched a formal review to address non-IP problems in October 2022, asking stakeholders to consider ways to improve robocall blocking and consumer warning tools for non-IP-based networks.
The technology to combat illegal robocallers on non-IP phone networks is still not there. In some cases, a non-IP network might be 'downstream' from the originating service provider, causing call authentication data from the SIP header to go missing.
In general, non-IP phone networks can't add or maintain digital information between connections. That means calls generated by or passing through these networks won't include STIR/SHAKEN verification data, including information from the voice service provider about the caller, the phone number they use, and the call itself. On top of that, it's challenging to verify call routing through non-IP phone networks.
The FCC has asked for input on two non-IP standards developed by the Alliance for Telecommunications Industry Solutions (ATIS), an organization that delivers standards and solves challenges for the ICT industry. These standards, suggested by the new ATIS Non-IP Call Authentication Task Force, could enable caller ID authentication over non-IP networks:
- Allowing non-IP providers to send and receive caller I.D. information over the internet on a separate track from the call.
- Providing more detailed information about calls over non-IP networks.
Pushback From Carriers
While phone carriers — like their customers — want to eliminate illegal robocalls for good, these companies don't want to upgrade existing landline technologies because it's complex and expensive. Lobby group USTelecom disagrees with the FCC explaining that authentication solutions for non-IP phone networks would be resource-intensive and detract from the eventual nationwide transition to IP network technology.
There's no guarantee that new standards like the ones proposed by ATIS would even solve authentication issues with non-IP technology. Perhaps, as USTelecom argues, it's best to wait until the industry fully transitions to IP networks.
But when will that happen?
Possible Solutions to Non-IP Network Authentication
While fully transitioning to VoIP seems like the most obvious solution to the problem of non-IP network authentication, this change is unlikely to occur in the U.S. any time soon. There are two possible solutions to call origination.
The Big Switch Off
The United Kingdom is currently phasing out ISDN (Integrated Services Digital Network) and Public Switch Telephone Network (PSTN) from their phone networks — a process called The Big Switch Off 2025. While this decision will primarily solve maintenance problems associated with old copper landlines, it would also eliminate non-IP network authentication concerns.
Something like The Big Switch Off wouldn't be possible in the United States because of infrastructure requirements for rural regions. The FCC and phone carriers must find alternative solutions to the non-IP network authentication problem.
Out-of-Band and In-Band Solutions
The FCC is currently considering out-of-band and in-band solutions to tackle non-IP network authentication:
- An out-of-band solution would require an originating service provider to upload a call's information to a secure location on the internet. The terminating service provider can then look up that information to verify a call.
- An in-band solution would require an origination service provider to work with the subsequent provider in the call path and share information about a caller and their right to use a phone number for a call.
ATIS says out-of-band and in-band aren't mutually exclusive. A single provider could combine the standards within its network, while several providers could use both standards across a call path.
At the time of writing, the FCC is seeking comments on the pros and cons of these potential solutions and whether additional measures are required to address non-IP network authentication issues. The organization will also consider implementation costs, potential security problems, and compatibility with STIR/SHAKEN.
Ongoing Call Authentication Efforts
While STIR/SHAKEN has reduced call spoofing, the problem still exists on non-IP phone networks. Technological limitations mean illegal robocallers can still reach people and trick them into handing over their personal and financial data. The FCC is determined to solve this issue and is currently evaluating potential call authentication solutions from ATIS and weighing up the pros and cons of out-of-band and in-band standards.
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