What Is STIR/SHAKEN?

STIR/SHAKEN is a set of protocols that phone carriers use to digitally sign individual calls so that the origin of a call can be validated by every carrier between you and the person you are dialing. The short version: when a call leaves your network, the originating carrier attaches a signature that says how confident it is that you have the right to use the number in your Caller ID spoofing field. Every carrier the call passes through can read that signature. If you run outbound campaigns, STIR/SHAKEN is the thing quietly deciding whether your calls reach a phone at all, so it is worth understanding even though most of the machinery lives at the carrier layer, not inside your dialer.

What the protocols actually do

The acronyms split a single job in two. STIR is the standard for signing a call with a token that ties the caller ID to the originator. SHAKEN is the framework that tells carriers how to deploy STIR across the real, messy network of trunks and gateways that connect them. Together they replace blind trust in caller ID with a chain of Call attestation that travels with the call from one Carrier to the next. The signing carrier rates how sure it is, and the terminating carrier verifies the signature before deciding whether to ring the phone, label it, or drop it.

For a VICIdial operator, the practical takeaway is that your numbers need to be properly registered with whoever signs your traffic. VICIdial ships code for the TILTX STIR/SHAKEN API so calls can be tagged as they originate, and we help clients line their numbers up with each carrier's signing requirements. This sits inside the bigger picture covered in our VICIdial compliance overview. STIR/SHAKEN came out of the same law that drives a lot of this, so it pairs naturally with what the TRACED Act is.

It helps to keep a few facts straight, because STIR/SHAKEN gets blamed for problems it does not cause and credited for ones it does not solve. A handful of things are true of every signed call:

• The signature is added by the carrier, not by your dialer. You influence it through number registration, not through a setting in the admin panel.
• It does not encrypt or change your audio. It only attaches an authenticated statement about who is allowed to use the caller ID.
• It does not, by itself, block a call. It hands the terminating carrier the information to decide, and that decision is where blocking and labeling happen.
• It travels the whole path. A weak link anywhere between origination and destination can knock down the grade your call arrives with.

Because the signing happens upstream, the most common mistake operators make is assuming a clean list and a polite script are enough. They help, but a call that arrives with weak attestation can still be filtered before anyone hears that script. Treating signing as a first-class part of your setup, rather than an afterthought, is what keeps the rest of your compliance work from being wasted.

Signing and verifying a call

sequenceDiagram
  participant D as VICIdial Dialer
  participant O as Originating Carrier
  participant T as Terminating Carrier
  participant P as Consumer Phone
  D->>O: Place call with caller ID
  O->>O: Sign call with attestation
  O->>T: Send signed call
  T->>T: Verify signature
  T->>P: Ring phone or label call

Your dialer hands the call to the originating carrier, which signs it with an attestation level. The terminating carrier checks that signature and uses it to decide how the call is treated on the consumer's screen. Nothing about this is visible to your agent, which is exactly why low attestation is so easy to miss until answer rates fall.

Getting signed correctly is mostly a matter of number registration and the right upstream relationships, and that is the part we set up for you. VICIfast ships compliant defaults and works with carriers so your calls are signed the way they should be. See pricing to get started.