Definition
Attestation levels are the three grades of confidence (A for full, B for partial, C for gateway) that an originating provider assigns when it signs a call under STIR/SHAKEN.
Full ("A") attestation means the originating provider knows its customer and has verified that the customer is authorized to use the calling number. Partial ("B") attestation means the provider knows the customer but cannot confirm their right to use that specific number. Gateway ("C") attestation means the provider is passing the call along from a source it cannot authenticate, such as an international gateway.
Attestation is a baseline trust signal and a prerequisite for most branded calling programs, so legitimate callers should structure carrier relationships to sign at full attestation. But it is unevenly available and imperfect. The seven largest U.S. carriers have plateaued at roughly 85% signed traffic between networks, while smaller carriers sit near 20%, and industry commenters in the FCC's 2025 STIR/SHAKEN review said "A" attestation is sometimes assigned to invalid or Do Not Originate numbers. The FCC has since proposed tying attestation decisions to Know-Your-Customer diligence.
How Consig handles it
Consig manages the carrier side of getting through, including caller ID and number reputation, through its carrier relationships and strategic partnerships rather than leaving it to each customer.