U.S. consumers receive over 200,000 unwanted calls per minute—and nearly half are illegal scams, which cost consumers more than $10.5B. As a result, trust in the public telephone network has declined to the point where nearly 90% of consumers decline calls from unknown numbers or caller IDs.

The U.S. government TRACED Act requires that STIR/SHAKEN be implemented in IP networks by June 30, 2021 and other governments are expected to follow with similar requirements. STIR/SHAKEN (Secure Telephone Identity Revisited/Secure Handling of Asserted Information Using Tokens) allows communication service providers (CSPs) to digitally sign calls from known trusted callers in a way that cannot be tampered with as the call flows through the network.


In an effort to reduce fraudulent, spoofed CLI telephone calls to consumers, the FCC has directed carriers to implement STIR/SHAKEN (Secure Telephone Identity Revisited /Signature-based Handling of Asserted information using toKENs)

Originating IP network provides caller authentication in the form of a cryptographic signature and attestation (see table). The cryptographic signature covers calling and called numbers, ensuring that “man in the middle” attacks cannot succeed.

Terminating IP provider verifies the call’s cryptographic signature.

Provider decides how to convey the verification results:

  • Attestation is used as one input
  • Optional CVT-based call analytics can be blended in as well

Terminating IP provider can trace the call back to the signing (originating) IP provider

NetNumber Guaranteed Caller extends the company’s previous solutions to address all commonly known trusted-call scenarios, enabling legitimate callers to participate in the STIR/SHAKEN trust network while locking out fraudulent callers. It is the industry’s most comprehensive approach to solving unwanted calls.

The NetNumber Guaranteed Caller family consists of five STIR/SHAKEN-based solutions. Contact us to find the one that meets your needs.

Guaranteed Caller National – implements the national level infrastructure needed to administer a country-level STIR/SHAKEN trust network.
Guaranteed Caller Service Provider – implements the functionality of signing and verifying known trusted calls, allowing service providers to ensure that the calls of their legitimate subscribers travel inside the STIR/SHAKEN network of trust.
Guaranteed Caller TDM-SHAKEN – extends Guaranteed Caller Service Provider to provide support for TDM/SS7 networks.
Guaranteed Caller Enterprise – extends the STIR/SHAKEN trust network to enterprises so that they can sign their calls with their company name, their corporate logo and the reason for their call.
Guaranteed Caller International – extends the STIR/SHAKEN trust network to CSPs outside of North America that terminate calls into the US and Canada.

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