This is not a STIR/SHAKEN Issue.
Wireless providers, including Verizon, use systems similar to NomoRobo to identify spam calls. These systems evaluate calls based on a scoring system. When calls exceed a certain threshold they are marked as SPAM, it is up to the Termination Provider receiving those scores to decide what scores should be marked as SPAM and what the tags state. It's important to note that these evaluations are largely based on the origin Caller ID (1NPANXXXXXXX) and are not directly related to STIR/SHAKEN protocols. This can be observed where some calls have the STIR/SHAKEN Checkmark on the cell phone but still marked as SPAM. The STIR/SHAKEN signing token doesn’t always make it from the originator to the termination provider due to complexities to the PSTN.
The most effective approach to combat this issue with AT&T, T-Mobile, and Verizon is to proactively register your Caller ID with freecallerregistry.com. This service is provided by TNS and communicates with Hiya, First Orion, and TNS — providers that service AT&T, Verizon, and T-Mobile — ensuring your number is less likely to be tagged as SPAM. For best results, submit your numbers in an 11-digit format, although 10-digit submissions are also accepted. Typically, numbers are cleared of SPAM tags within 2-5 days; however, they may be re-flagged based on calling patterns or user reports.
It's advisable for legitimate businesses to register their numbers before they are tagged as SPAM. Certain businesses, like debt collectors or lead generators, may find it more challenging to avoid SPAM tags. Strategies such as acquiring new numbers, gradually increasing usage ("warming up"), and rotating numbers can help maintain a clean status.
Starting January 15th, 2024 we have seen an industry wide uptick in the number of calls being marked as SPAM on the Verizon Network or providers who use HIYA and First Orion. Numbers that are not registered in their databases may automatically be marked as SPAM. The process to remove numbers as SPAM takes 2-5 days. freecallerregistry.com submits to TNS/First Orion/HIYA all at once. You will receive email verification from each of them after submission.
On February 8th, TNS identified a bug that was introduced to their code that greatly increased the likelyhood of calls being marked as SPAM industry-wide.
Multiple companies provide analytics, each with their own tracking and radar systems. It is possible your numbers are being blocked or labeled as SPAM due to false flagging.
Free Caller Registry: (First Orion, Hiya, and TNS) This free portal helps entities reach the analytics companies that support the major wireless carriers in the US. The Website is operated by TNS, and works directly with Hiya and First Orion who provide services for AT&T, T-Mobile, and Verizon.
Submit numbers as 11 digits, 10 digit submissions are not likely to impact SPAM statuses.
Note: Analytics companies will review the requests and may still flag calls depending on their analytics, termination user spam reports, or independent research.
If you know the carrier/provider that may be falsely identifying, blocking, or labeling your number(s) in the databases that feed this information, please contact them directly using the contact information below.
Note: When sending requests to the NoMoRobo and YouMail email addresses listed above - please include the calling number, name associated with the number, and details regarding why it is not a spam number.
Separately, if you believe your customer is a victim of spoofing, you can visit the following URL
https://www.fcc.gov/consumers/guides/spoofing-and-caller-id
If you are instead suspecting calls that are coming from spoofed numbers see our FAQ article - How do I handle calls from suspected spoofed DIDs?