Sending SMS from 10-digit long code numbers that are not registered under an approved A2P 10DLC campaign is no longer simply a policy violation with future consequences. Carriers have been actively filtering unregistered traffic since 2021, and the filtering rates have increased each year as carrier systems have become more sophisticated. By 2026, unregistered 10DLC traffic faces filtering rates of 20 to 30% on AT&T and T-Mobile networks, meaning roughly one in four messages never reaches the recipient despite Twilio reporting a successful submission to the carrier network.
How Carriers Identify and Filter Unregistered Traffic
Carrier networks receive A2P 10DLC registration data from The Campaign Registry and cross-reference every inbound SMS submission against their registered campaign database in real time. A message submitted from a 10-digit long code that has no campaign registration associated with it is classified as unregistered traffic and routed through a secondary evaluation pathway where filtering thresholds are much more aggressive. In some cases, unregistered traffic is throttled to near zero throughput during peak hours when spam filtering resources are under load. Carriers also use unregistered traffic patterns to build profile data on unregistered sending numbers, and numbers with high-volume unregistered sending history may be blocked entirely rather than just filtered. Twilio returns a delivered status for messages that were accepted by the carrier network but subsequently filtered, which means delivery reports in your application code do not reveal the true delivery rate for unregistered traffic.
The Financial Cost of Unregistered Sending
Beyond the deliverability cost of filtering, sending unregistered 10DLC traffic carries a direct financial penalty that Twilio applies to unregistered message segments. Since 2023, Twilio has charged an additional surcharge per message segment for SMS sent from unregistered 10DLC numbers, on top of the standard per-segment rate. For businesses sending tens of thousands of messages per month, this surcharge adds up quickly and in many cases exceeds the total cost of A2P 10DLC registration many times over. A business paying the unregistered surcharge for six months could have funded its entire A2P registration and campaign fees multiple times over. This creates a situation where businesses that delay registration to avoid compliance costs are actually paying more in surcharges than they would have paid for registration while simultaneously receiving worse deliverability.
Risks to Your Twilio Account from Sustained Unregistered Sending
Sustained unregistered sending creates account-level risks beyond per-message filtering. Twilio's Terms of Service require compliance with carrier messaging policies, and accounts that continue sending high volumes of unregistered traffic after receiving warnings may have their messaging permissions restricted or their account suspended. Carrier complaints about spam from unregistered numbers are attributed at the account level, and a pattern of complaints can result in Twilio proactively restricting your messaging capability to protect the deliverability of other Twilio customers who share infrastructure. Additionally, if a carrier blocks a specific set of phone numbers due to unregistered high-volume sending, those numbers may be permanently flagged in carrier systems and cannot be recovered by registering them after the fact, requiring you to provision new numbers and start the registration process from scratch.
How to Check Whether Your Numbers Are Registered
The quickest way to audit whether your phone numbers are registered is to navigate to the Twilio Trust Hub in your console and review the A2P section for campaign registrations and number assignments. Each number in your Twilio account should appear in at least one active campaign's number assignment list. If you have numbers in your account that are not listed in any campaign assignment, those numbers are sending unregistered traffic and need to be either assigned to an existing approved campaign or included in a new campaign registration if their use case differs from your existing campaigns. Numbers can be exported from your Phone Numbers section and cross-referenced against campaign assignment lists using the Twilio API if you have a large number pool. Running this audit before the next campaign launch rather than after discovering a deliverability problem gives you time to complete registration before it affects your sends.
Conclusion
Every day of unregistered sending is a day of paying higher per-message fees for lower delivery rates, and the longer it continues the more reputational damage accumulates on your sending numbers. Speak with our compliance team and we will audit every number in your Twilio account and complete all outstanding registrations.
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