Call attestation is the information your carrier can authenticate about you, such as where you are calling from and your right to use your phone number. If a carrier can’t verify key information about a call, that can have a powerful impact on whether they label the call as spam or even block it.

Carriers communicate a call’s attestation through tokens. The caller’s carrier sends a token to the recipient’s carrier, which may decide to label or block the call. The highest level of token communicates confidence in the caller’s right to use their phone number, while the lowest indicates a suspicious level of uncertainty.

A normal person making a call from their home phone will almost always have the highest level of attestation token. That means that any lower-level token is immediately suspicious and very likely to be labeled or even blocked. Poor call attestation can be fatal to your cold-calling efforts.

Fortunately, it is possible to improve your call attestation. Because attestation happens between your phone and the carrier, the primary way to improve attestation is to work with your dialing service and consider switching services if they don’t guarantee A-level attestation.

What Are Call Attestation Tokens?

Call attestation tokens are how carriers communicate the amount of trust they have in you, the caller. There are three levels of tokens, each of which signals a different degree of confidence in the caller. 


An A-level token signals full call attestation. That means the carrier has complete information about who the caller is, what number they are using, and their right to use the number they’re calling from. People buying their phone numbers and calling through BatchDialer always have A-level call attestation. While A-level attestation doesn’t mean no calls will ever be blocked, it’s a basic necessity for any high-volume calling.


B-level attestation tokens communicate partial attestation. This token means that the carrier you’re calling through can verify your identity, but they can’t confirm your right to use the number you’re calling from. Calls from many business telephone systems can receive B-level tokens, which is something you should ask about if using a private branch exchange (PBX) to call through. B-level attestation is a high-risk factor that can cause carriers to label your calls as spam.


Tokens at the C-level indicate the lowest degree of confidence possible. Calls with C-level tokens do not have verified sources, which means it is impossible to know whether the caller has the right to use their number. If your calls have C-level tokens, it is possible that carriers are blocking them before they even reach your intended prospects.

Impacts of Call Attestation

Call Blocking

Many carriers automatically block calls they deem sufficiently suspicious. While the exact formula carriers use can vary between each provider, a call’s attestation is always a critical factor. Calls with C-level tokens and no other indications of suspicious activity may be blocked for that reason alone. 

Three carriers make up almost 99% of the total US wireless market: T-Mobile, AT&T, and Verizon. Each of these carriers has a free automatic call blocking service that relies on data like attestation tokens when determining which calls to block. 

Many consumers also use third-party call blocking applications. Like carriers’ services, these apps use a combination of factors to choose which calls to block, which relies more heavily on user feedback but also takes attestation into account. Typically, they try to be even more strict than carriers’ services, which means that a good call attestation could be even more important for these users.

Call Labeling

Whenever you see “Scam Likely” on a call from a number you don’t know, you’re benefitting from call labeling. Labeling is how carriers and third-party applications warn users that someone suspicious might be calling. It’s a less aggressive approach than call blocking, but it can still severely impact whether people answer your calls.

Call attestation has a strong impact on whether your call receives a negative label. While a call with a B or C token might not be outright blocked, it’s very likely that it will be labeled as spam. Labels like “Potential Spam” have a strong effect on answer rates–after all, few people will answer calls they already know would be a waste of time.

Unfortunately, sometimes carriers apply these labels incorrectly–according to FCC estimates, about 24% of the time. That means you need to do anything in your power to avoid being one of those legitimate callers that are mislabeled by an overaggressive system. A key part of any strategy to improve your call labels has to be ensuring that all of your calls will go out with A-level attestation tokens.

How to Improve Your Attestation

It’s fine to say that attestation is important to improve, but how do you actually guarantee that you’ll have the highest attestation possible on every call? You need to rely on a quality dialing service.

When most people make calls on their personal phones, they’re dialing through their carrier. But at the enterprise level, it’s much more common to use a separate program to handle calls at scale. These dialing services are intermediaries between the caller and the carrier, and that level of separation can create problems for call attestation.

Some dialing services may send incomplete information to carriers. If you’re having trouble with your call attestation, it’s likely that the issue is with your dialer not telling the carrier everything they need to know about your identity and your right to use your phone number. While it’s possible that this is just a technical problem with the dialer, it’s possible that you should take a look at alternative dialers that can guarantee A-level attestation on all your calls.

That is why BatchDialer makes sure that every call from a BatchDialer number goes through with an A-level attestation token. Attestation tokens might not guarantee that every call goes through unblocked and without a label, but they are the foundation for any high-volume dialing strategy.


  • Carriers use attestation tokens to signal their confidence that they know who a caller is and that they have a right to use their phone number.

  • Call attestation is a key factor in whether your calls are automatically blocked or labeled as spam by carriers.

  • The best way to ensure high-level call attestation consistently is with a quality dialing service like BatchDialer.