Carrier filtering is blocking legitimate SMS. The operators getting through are doing three things differently

A business registers its number, writes a plain appointment reminder and sends it. The text never arrives. Nothing bounces back. Somewhere between the sender and the phone, a filter simply drops it.

US carriers filter business text messaging for three main reasons: spam volume, complaint rates and messages that do not match the business that registered them. In 2026 they tightened enforcement on several categories of business messaging, according to Thomas Driscoll, founder and CEO of the SMS infrastructure platform Sendivo . To a legitimate sender, the filtering can look random. Driscoll says it is not.

“Carrier filtering isn’t random. The businesses that get through understand the rules: registration, opt-in, content that matches the brand, and monitoring. The ones that treat SMS like email get blocked,” said Driscoll.

Sendivo serves more than 1,000 users sending across US carriers. That gives Driscoll a direct view of what gets traffic blocked and what gets it through. Three practices separate the two.

The industry calls business texts sent from ordinary ten-digit numbers application-to-person, or A2P, messages. They go through 10DLC registration. A business first registers its brand, including its legal identity. It then registers each campaign: what the messages are for, sample content and how recipients opt in.

Carriers use that record to decide how far to trust the traffic. It is also where a lot of SMS filtering starts. A campaign registered for appointment reminders that sends promotions gives the carrier a reason to block it. So does a brand name that does not match the company named in the messages. The same filters exist to stop scam texts , which is why they also catch legitimate senders who look inconsistent.

The first practice is the least glamorous. Register accurately, then keep sending what the registration describes. The content of each message should match the registered business name and the registered use case.

Sendivo learned this at the platform level. A carrier partner flagged the platform because some customers’ message content did not match their registered business names. The team did not argue. Within days it shipped a filter that blocks messages whose content does not match the registered brand, and it removed the accounts responsible.

“The carrier is the customer you can’t fire. When they tell you something in your traffic doesn’t match, the answer isn’t a debate. It’s a fix,” said Driscoll.

Sendivo now vets every new campaign with AI before it reaches the carrier, and guides customers through A2P registration one to one. The company reports a campaign approval rate of close to 100%.

Carriers watch complaint rates closely. A recipient who never asked for a message is the quickest route to a complaint, so opt-in has to be real. The person agreed to receive texts from that business, for that purpose.

When a recipient complains or replies to stop, sending should end at that first signal. Waiting for a second or third complaint is how a sender’s reputation erodes.

“Every complaint is a signal the carrier sees as well. If you keep sending after it, you’re telling the network you can’t be trusted with its customers,” said Driscoll.

The third practice is monitoring. Delivery metrics tracked per campaign, rather than per account, show when one campaign starts to fail. A falling delivery rate is often the first sign that a carrier has started filtering. Pulling that traffic early limits the damage to everything else the business sends.

On a shared platform, the stakes are higher. Every sender on a wholesale platform shares one reputation with the carriers, so one non-compliant sender can hurt SMS deliverability for everyone else. When enforcement tightened in 2026, Sendivo removed non-compliant senders and added pre-send content filtering. Deliverability across its network held.

“On a platform, reputation isn’t individual. If one sender is sending messages the carrier doesn’t want, every other business on the network pays for it. Policing that traffic is our job, not the carrier’s,” said Driscoll.

None of the three practices is new. In Driscoll’s view, what changed in 2026 is how strictly carriers enforce them. Businesses and agencies running SMS campaigns that register accurately, respect opt-in and watch their own delivery numbers are the ones whose messages still arrive.

Contributed article. Not produced by the TNW newsroom and does not reflect the editorial stance of TNW.