What is STIR/SHAKEN?
Last verified · by Topcalls Team
Definition
STIR/SHAKEN is a set of telecom standards that cryptographically sign the caller ID on a call, so the receiving carrier can confirm the number wasn't spoofed before the phone rings.
What it is
STIR/SHAKEN is two specifications working together. STIR (Secure Telephone Identity Revisited) defines how a caller's originating carrier attaches a signed digital token to a call. SHAKEN (Signature-based Handling of Asserted Information Using toKENs) is the framework that carries that token across the SIP network so the terminating carrier can check it. The signature travels with the call and proves two things: the number displayed was authorized to make the call, and nobody altered it in transit.
The part that actually affects your calls is the attestation level, and there are three. Full attestation (A) means the carrier knows the customer and confirms they own the number being displayed. Partial attestation (B) means the carrier knows the customer but can't vouch for that specific number. Gateway attestation (C) means the call entered the network from somewhere the carrier can't verify at all. An A gets treated as trustworthy; a C is a prime candidate for a "Spam Likely" label or an outright block.
For outbound sales, this is not a compliance footnote, it is your connect rate. Carriers and analytics services like Hiya, TNS, and First Orion feed attestation into the spam scoring that stamps "Scam Likely" on a number. A B2B or B2C team dialing from numbers that only earn B or C attestation will watch pickup rates fall as more of their IDs get flagged, regardless of how legitimate the calls are. Getting to full A attestation is the single biggest lever most outbound teams have over caller reputation.
STIR/SHAKEN is mandated in the US (FCC, since June 2021) and Canada (CRTC), and equivalent caller-ID authentication is spreading through other markets. It only works on IP-based (VoIP/SIP) call paths, so calls that still traverse legacy TDM segments can lose their signature along the way, which is one reason a perfectly legitimate call can arrive without a valid attestation.
Topcalls originates calls over authenticated SIP so outbound campaigns can reach full attestation instead of leaking to a "Spam Likely" label, and it pairs that with local presence dialing and number rotation to keep caller reputation healthy. All of it is billed at one all-inclusive $0.35/min rate, with telephony, recording, and transcription already included rather than metered as add-ons.
Frequently asked questions
Does STIR/SHAKEN stop my calls from being marked spam?
It's the foundation, not a guarantee. Full A attestation tells carriers the call is authenticated, which keeps you out of the worst spam buckets, but call frequency, complaint rates, and how many people decline your calls still feed the reputation score analytics providers assign to each number.
What do attestation levels A, B, and C mean?
A (full) means your carrier confirms you're authorized to use the displayed number. B (partial) means the carrier knows you but can't confirm that specific number. C (gateway) means the call came from an unverified source. A is trusted, C is the most likely to be blocked or labeled.
Is STIR/SHAKEN legally required?
Yes, in the US and Canada. The FCC required voice providers to implement it in their IP networks starting June 2021, and Canada's CRTC has a parallel mandate. Many other countries are rolling out comparable caller-ID authentication.
Why does a real, legitimate call sometimes show no attestation?
STIR/SHAKEN signatures only survive on all-IP call paths. If a call crosses a legacy TDM segment on its way to the recipient, the signature can be stripped, so a genuine call can land with a lower attestation than it started with.
How do I get full attestation on my outbound numbers?
Originate calls through a provider that authenticates the numbers you're authorized to use over a fully IP-based path. Topcalls handles this at the network level, so campaigns dial from authenticated numbers rather than routes that only earn partial or gateway attestation.
How is STIR/SHAKEN different from a DNC or TCPA check?
STIR/SHAKEN authenticates who is calling. TCPA and DNC rules govern whether you're allowed to call a given person at all. You need both: authentication protects your connect rate, compliance protects you from legal liability.
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