A2P 10DLC: why your texts are being filtered and nobody told you

Texts started performing worse. Not dramatically — reply rates drifted down, a few customers mentioned they never got the confirmation, and you put it down to a slow month. Nothing in your dashboard said failed.

If that describes you and your business texts from an ordinary ten-digit number, the first thing to check is your A2P 10DLC registration status. Not the last thing, after you have rewritten your templates and blamed your audience. The first.

A2P means application-to-person: a message sent by software rather than typed by a human. 10DLC means it went out over a ten-digit local number — the normal-looking number your customers recognise, as opposed to a short code or a toll-free number.

US carriers built this standard because that combination is what spam uses. Their answer was not to block it but to demand identification: tell us who you are and what you intend to send, and we will treat you accordingly.

This is where most people get stuck, because doing one and assuming you are finished is easy.

• Brand registration establishes who you are — the legal business identity behind the traffic.
• Campaign registration describes what you send: the purpose of the messages, how people opt in, how they opt out, how they reach support. A standard brand can register several campaigns under it.

A registered brand with no registered campaign is not registered traffic. Both have to exist before your messages are treated as legitimate.

Carriers apply surcharges to unregistered traffic and subject it to heavier filtering and lower throughput. You pay more to be delivered less.

Throughput is a daily volume ceiling, and it varies by how you are registered — a sole proprietor registration carries a much lower daily limit than a standard brand, whose allowance scales with sending behavior. T-Mobile’s trust score is the metric most often cited for determining those long-code limits.

For a service business sending a few hundred replies a month, the ceiling is rarely the problem. The filtering is.

Two comparisons will usually settle it without any special tooling.

• Delivery receipts against reply rates on the same segment. Deliveries holding steady while replies fall is an audience or content problem. Deliveries falling is a carrier problem.
• Text against email over the same period, to the same kind of contact. Email is not carrier-filtered this way. A drop confined to one channel, with no change in what you send or who you send it to, is the signature.

Content matters too — link shorteners, all-caps, and certain regulated words attract filtering independent of registration. But registration is the cheap thing to rule out first.

Registration and consent are separate regimes and satisfying one says nothing about the other. Carriers care whether you are identified. The TCPA cares whether the recipient agreed. A perfectly registered campaign messaging people who never opted in is a compliant pipe carrying a liability.

Your registration does describe your opt-in and opt-out process, which means the two meet at exactly one point: what you told the carrier you do should be what you actually do.