Call Origination in STIR/SHAKEN, Explained Step by Step

The FCC required STIR/SHAKEN implementation in 2021, and businesses have had to adapt. Those that haven’t risk unanswered outbound calls or calls that never reach the intended person. Today, falling short can mean lost revenue, reputational damage and even denial of service.

To understand why, it helps to look at how a call is originated and authenticated.

What call origination is

A call is originated when someone places it and it’s sent to their phone service provider, which routes it towards the recipient’s device. Ideally, the origination information helps the provider understand who placed the call and whether it poses a risk. If the origination doesn’t meet STIR/SHAKEN standards, the call may be terminated or the recipient may be warned not to answer.

What STIR/SHAKEN is trying to achieve

The primary goal is a call authentication framework that prevents spoofing. Spoofing lets scammers borrow the numbers of trusted organisations, like hospitals, schools and credit unions, because people who trust a number are more likely to share personal information.

A secondary goal is gathering information that caller ID systems can use to help people decide whether to answer. A number making hundreds of calls a day, for example, might be labelled as a robocall or spam.

The seven steps of STIR/SHAKEN authentication

1. The caller places the call.
2. The originating service provider (OSP) checks its records to verify where the call is coming from.
3. The OSP assigns an attestation rating: A (full), B (partial) or C (gateway).
4. A SIP header is created containing the attestation rating, a timestamp, the calling number and the called number.
5. The call travels across networks to the terminating provider, sometimes passing through several carriers along the way.
6. The terminating service provider (TSP) receives the call and evaluates it.
7. The TSP decides whether to add a label, block the call or deliver caller details, including Rich Call Data, to the recipient’s device.

Staying compliant in your dialing

Businesses that depend on outbound calls need to work within this system, or customers are unlikely to answer. Accurate caller ID improves answer rates, strengthens your brand and leads to more revenue and happier customers. Five practices make the biggest difference.

Use reliable carriers

A non-compliant provider can put your own compliance at risk. Choose STIR/SHAKEN-compliant providers that originate calls properly and support strong attestation.

Aim for A attestation

Anything below A makes it harder to reach customers and leads. An attestation tester shows your current ratings so you can work with your provider to improve them.

Follow call compliance rules

The FCC continues to widen its enforcement. Beyond fines, non-compliance can lead to blocked calls and warnings telling consumers not to answer.

Dial ethically

Check your lead sheets to avoid unwanted contacts and make sure your dialing meets federal and local rules: check the National Do Not Call Registry, check your internal do-not-call list and be cautious with leads bought from third parties.

Use enhanced caller ID

Rich Call Data and branded caller ID help your calls carry accurate information, including your logo and reason for calling, which encourages people to answer.

How Spam Checker helps

Spam Checker monitors dialing activity, flags and caller ID displays, with real-time reporting so you can address problems as they appear. Device Cloud shows screenshots from real phones on popular carriers. Ongoing monitoring is the most reliable way to stay compliant and protect your brand.

What’s inside the SIP header

The SIP header created at origination is a compact record of the call: its attestation rating, a timestamp, the calling number and the number being called, all wrapped in a digital signature. Each network the call passes through can read it, and the terminating provider uses it to check that nothing has been tampered with. If the signature is missing or invalid, the call is treated with much more suspicion.

Why multiple networks complicate things

Calls often travel through several carriers before they reach their destination. Each hand-off is a point where information can be lost, particularly if part of the path still uses older, non-IP technology. That’s one reason the framework has been extended over time, and why the quality of your providers and routes matters as much as your own setup.

How the terminating provider decides

The terminating provider combines the attestation rating with its own analytics: the number’s history, complaint levels, calling patterns and data from partners. A well-signed call from a healthy number is likely to be delivered cleanly, possibly with Rich Call Data. A poorly signed call from a number with a weak reputation may be labelled or blocked.

Frequently asked questions

Who assigns the attestation rating?

The originating service provider, based on what it knows about the caller and the number.

What does the terminating provider do?

It verifies the call and decides whether to label it, block it or show caller details.

Can a call pass through several networks?

Yes. Calls often travel through multiple carriers before reaching the terminating provider.