Guide
STIR/SHAKEN without the engineering
Most explanations of STIR/SHAKEN are written for network engineers: certificates, SIP headers and identity tokens. A sales team needs much less. You need to know what the three attestation levels mean, who decides which one your calls get, what attestation can and can't do for answer rates, and which parts are in your hands. That's what this guide covers, for the US and Canada, as of November 7, 2026.
What is STIR/SHAKEN, in plain terms?
STIR/SHAKEN is a way for phone networks to sign the caller ID on a call, so the network receiving the call can check who vouched for it and how confident they were that the caller was allowed to use that number.
Before it, caller ID was just a number the calling side typed in, and nothing stopped a robocaller from typing in anyone's number. STIR (the signing standards) and SHAKEN (the framework carriers use to apply them) add a digital signature from the originating provider. The receiving provider verifies the signature and passes the result to its call analytics, which help decide whether to label, block or simply deliver the call.
In the US, Congress required it in the TRACED Act (2019), and the FCC set June 30, 2021 as the main deadline for voice providers' IP networks, with later dates for some smaller providers and separate rules for networks that still use older technology.
What do A, B and C attestation mean?
Attestation is the confidence level the originating provider signs a call with: A is full attestation, B is partial and C is gateway.
- A, full attestation: the provider started the call, knows the customer making it and has verified that the customer is authorized to use the calling number. A number your calling provider assigned to you typically gets A.
- B, partial attestation: the provider knows the customer but can't verify their right to the number shown, for example when a customer displays a number it bought from a different company.
- C, gateway attestation: the provider can only say where it received the call, such as from an international gateway or another network that didn't sign it.
- No signature: some calls arrive unsigned, often because part of the route still uses older, non-IP links.
Who decides which attestation your calls get?
The provider that puts your calls onto the phone network decides, based on whether it knows you and whether it can verify that the numbers you show belong to you.
For a team using a dialer or CRM, that's the dialer's carrier, not your mobile phone company and not the CRM itself. FCC rules let a provider hire a third party to do the signing, but since 2025 the calls have to be signed with the provider's own certificate, and the provider makes the attestation decision. That closed a loophole where providers lent out someone else's identity.
The simplest route to A attestation is to call from numbers your calling provider has assigned to you. Showing a number that lives with another company, such as your office line from a different carrier, often gets B unless your provider can verify it.
Does STIR/SHAKEN attestation change answer rates?
Indirectly: attestation is one input to the analytics that decide spam labels and blocking, so better attestation lowers one risk, but it doesn't make people answer and it doesn't guarantee a clean label.
Verizon, for example, says it doesn't label calls based only on caller ID authentication. Analytics engines also weigh calling volume, call length, complaints and number history, which is why a fully attested number can still show as Spam Likely. Some phones and carriers show a 'verified' mark on fully attested calls, which can reassure the person who sees it.
No carrier publishes figures on how much attestation changes answer rates, so be wary of anyone quoting a precise lift. Treat A attestation as necessary but not sufficient: get it, then fix the calling pattern and register your numbers. Our guide to why calls show as spam covers the rest.
How does STIR/SHAKEN work in Canada?
Canada uses the same framework: the CRTC required Canadian voice providers to implement STIR/SHAKEN for IP-based calls by November 30, 2021, under Compliance and Enforcement and Telecom Decision CRTC 2021-123.
The CRTC first set the goal in Telecom Decision CRTC 2018-32 as part of its measures against caller ID spoofing, and it has separately required providers to block calls whose caller ID is impossible under the numbering plan (Compliance and Enforcement and Telecom Decision CRTC 2018-484). For a Canadian sales team the practical advice is identical to the US: call from numbers your provider assigned to you, register them and keep the calling pattern clean.
What can a sales team control, and what can't it?
A team controls the numbers it calls from and how it uses them; it doesn't control the networks between it and the person it's calling.
- You control: calling from numbers your provider assigned to you, so they can be fully attested.
- You control: how many calls each number makes, how long phones ring, how many silent drops you leave and how you handle opt-outs, which drive complaints.
- You control: registering each number with the Free Caller Registry and Verizon's feedback site, and branded caller ID if you want it.
- You can ask: your provider which attestation level your outbound calls get, and whether it shows in your call records.
- You can't control: whether a signature survives older, non-IP links on the way to the person.
- You can't control: how the receiving carrier or phone displays a call, or how its analytics engine scores your number.
How does STIR/SHAKEN relate to local presence and spoofing?
STIR/SHAKEN is the technical side of the legal line between local presence and spoofing: a local number your provider assigned to you can be fully attested, and a spoofed number can't.
That's why honest local presence uses real numbers you own rather than numbers built to look local. Our guide to local presence vs spoofing covers the law; our local presence dialing guide covers how to run it well.
How does STIR/SHAKEN work with TopReach?
TopReach calls go out from numbers your team buys in TopReach, through its carrier partner, Twilio, and assigned to your workspace, which is the arrangement full attestation is designed for.
Local presence picks only from those numbers, matched to each lead's area code, or else their province or state, so there's no spoofed or borrowed caller ID in the mix. TopReach doesn't show the attestation level of each call in the app, so if you need to confirm it, ask TopReach. Registering your numbers and keeping the calling pattern clean stay with your team.
