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STIR/SHAKEN: proof of who is calling
STIR/SHAKEN is the framework carriers use to fight caller ID spoofing. The provider that starts a call signs it with a certificate, and the provider that delivers it checks that signature before the phone rings.
Level A: Full attestation
Calls from CarrierX-rented numbers
Vouches for: Where the call entered, Who the customer is, Their right to the number.
Level B: Partial attestation
Customers' own third-party endpoints
Vouches for: Where the call entered, Who the customer is.
Level C: Gateway attestation
Endpoints resold by CarrierX partners
Vouches for: Where the call entered.
Why it matters
A signature that travels with every call
STIR/SHAKEN is certificate-based: the originating provider attests to the call and signs it, and the terminating provider verifies the signature before delivering it.
Fewer spoofed calls
Terminating providers can reject or flag calls whose caller ID cannot be verified, which helps reduce robocalls and impersonation.
Calls that can be traced
Attestation identifies the originating provider, so other providers and authorities can trace suspected illegal robocalls to their source.
A regulatory requirement
The FCC required most US voice service providers to implement STIR/SHAKEN in the IP portions of their networks by June 30, 2021.
The process
How a call is checked
Every signed call passes through the same four stages, from the network it starts on to the network that delivers it.
The caller dials
The call is placed on the originating provider's network.
The originator attests
The originating provider checks the call source and calling number, and chooses attestation level A, B or C.
The call is signed
A digitally signed Identity header is added to the call, carrying the attestation level and an identifier for the originator.
The receiver verifies
The terminating provider checks the signature against the originator's public certificate, then completes, flags or rejects the call.
CarrierX
How CarrierX handles STIR/SHAKEN
As a certified communications service provider, CarrierX complies with the FCC's requirements and can attest calls and add the attestation to the call data.
Full attestation on CarrierX numbers
Outbound calls from DIDs rented from CarrierX are signed with full (A) attestation.
Customer and partner traffic
Calls from third-party endpoints owned by CarrierX customers get partial (B) attestation; endpoints that CarrierX partners resell get gateway (C) attestation.
Verification on inbound calls
CarrierX verifies incoming signatures and records the attestation level, originator ID and result on the call detail record.
Your rules for the result
Call flows can mark verified callers as trusted, add a warning when a call was not verified, and reject calls that fail verification.
Any role in the chain
CarrierX can act as the originating, intermediate or terminating provider, and applies the procedures each role requires.
Questions
Common questions
STIR/SHAKEN
Talk through attestation for your traffic
Book a call with the CarrierX team to go over how your calls are signed and how inbound calls are verified.