Illegal robocalls are currently the number one source of consumer complaints at the FCC. What was once an annoyance has become a plague to U.S consumers receiving billion of robocalls every month. Both the FCC, through rule-making, and Congress, through legislative initiatives, have been active to address this problem, and to address it soon.

While bills in the House and Senate progress thru committees, the FCC continues to move forward with parallel activity.  The FCC recently issued a Declaratory Ruling clarifying that voice service providers may:

  • As the default, block calls based on call analytics that target unwanted calls, as long as their customers are informed and have the opportunity to opt out of the blocking.
  • Offer customers the option to block calls from any number that does not appear on a customer’s “white list” or contacts list, on an opt-in basis.

In conjunction with the Declaratory Ruling, the FCC issued a Third Futher Notice that:

  • Proposes to create a safe harbor for voice service providers that block calls for which Caller ID authentication fails and seek comment on extending the safe harbor to the blocking of calls that are unsigned.
  • Proposes to require voice service providers that block calls to ensure that emergency calls reach consumers.
  • Seeks comment on protections and remedies for callers whose calls are erroneously blocked.


To overcome the influx of unwanted calls in the service providers network, the industry has created two new standards: STIR (Secure Telephone Identity Revisited) and SHAKEN (Signature-based Handling of Asserted information using toKENs) standards.  Together, these two standards, create the framework to ensure every SIP-signaled call has a certificate of authenticity attached to it — a kind of digital signature — that allows service providers mitigate unwanted robocalls and prevents bad actors from using Caller ID spoofing.  With STIR/SHAKEN, service providers can restore their end customer’s trust in validity of caller ID.

Ribbon and Neustar Caller Authentication and Verification

Ribbon’s STIR/SHAKEN solution includes our award winning SBC and PSX  that have been validated on their effectiveness of the caller authentication standards (“Secure Telephone Identity (STI) Test Plan” (TLT-2018-00010), and Authentication and Verification Services)developed by the Internet Engineering Task Force (IETF) and ATIS. 

Ribbon has partnered with Neustar, a global information services provider, who provides a complete STIR/SHAKEN solution for the certificate repository, authentication and verification services, and associated management. 

In our jointly tested STIR/SHAKEN solution, the Ribbon SBC will generate and pass an identity header/signature to the authentication server via the Ribbon PSX.  Neustar will perform the authentication and verification services and send back verification of the signature to the PSX will receive, which in turn will pass that back to the SBC. The SBC has flexible handling of error conditions, e.g.  “reject the call”, “continue with the call”, “continue with the call and remove Identity header” if signature verification fails.  

Together, Ribbon and Neustar are leading the way with advanced solutions to protect consumers from unwanted calls and give them more control over the calls and texts they receive.

STIR-SHAKEN Architecture