STIR/SHAKEN attestation: A, B and C levels explained

Understand STIR/SHAKEN caller ID authentication and A, B, C attestation in US voice calling without confusing authentication with spam reputation. This guide focuses on decisions a working team can test, rather than promises about a single provider. The right approach depends on your destination markets, team size, and how callers and customers use the service.

What STIR/SHAKEN checks

STIR/SHAKEN is a framework for authenticating caller ID information in supported IP voice networks. It does not itself determine whether a call is wanted.

Begin by documenting the existing process: who owns the contact, what happens when a call connects, and what the next agent needs to know. A simple written baseline helps identify whether the proposed change solves a real problem.

Practical example: For example, a five-person outbound team might discover that its main issue is incomplete callback notes rather than the time needed to dial.

A, B and C attestation

Attestation levels relate to how much confidence the originating provider has in the caller and the asserted telephone number. They are not a general quality score for a business.

Run a controlled trial with real staff and realistic call scenarios. Record what works, what fails, and any extra administrator work before moving the entire team. Consider customers who call back as well as agents making calls.

Practical example: A realistic test should include one successful call, one failed connection, an inbound callback and an agent handover.

Why attestation is not a spam cure

A fully authenticated call may still receive a spam label based on analytics, complaints or calling behavior. Authentication and reputation are related but separate.

Evaluate the feature within the wider customer journey rather than in isolation. Make sure the records are understandable, the assigned person can take action, and the business can explain the process to a new employee.

Practical example: If a customer asks not to be contacted, the workflow should record and enforce that request even when a different colleague takes over.

What a business can do

Use authorized caller IDs, keep account verification current and ask the provider how attestation is handled. Do not attempt to impersonate numbers you do not control.

Define who will maintain this workflow and how exceptions will be handled. Schedule a short review after launch, using customer feedback and correctly interpreted call data to make improvements.

Practical example: A one-page operating guide and a weekly review are often enough to expose problems while the deployment is still small.

Implementation checklist

1. Write down the customer problem you want to solve and choose one measurable outcome.
2. Check destination coverage, account permissions, pricing conditions and any applicable consent rules.
3. Assign one person to own the pilot, test both successful and unsuccessful calls, and verify callbacks.
4. Train agents on notes, call outcomes and follow-up responsibilities.
5. Review actual customer results before expanding the workflow to more seats.

Next steps for your team

For additional context, read our guides on spam label troubleshooting and Do Not Call fundamentals. If you are comparing platforms, review the Dialsyx product tour, verify the features needed for your market and check current plan details before making a decision.