What is 10DLC?

10DLC stands for 10-Digit Long Code. It is the US registration system for A2P (Application-to-Person) SMS: messages sent by software to people, as opposed to two people texting each other. If your business sends texts to US phone numbers, 10DLC applies to you.

This page explains why the system exists, how a registration is reviewed, and where Sent fits in, so the requirements in the 10DLC Registration Guide read as a coherent system rather than a list of arbitrary rules.

Why carriers built a registration system

For years, businesses could send SMS from regular 10-digit numbers with no registration required. Carriers (AT&T, Verizon, T-Mobile) couldn't tell a legitimate business from a bot farm, so in 2019 they built a gating system: unregistered A2P traffic is filtered or throttled, and registered traffic is treated as legitimate.

Registration happens through TCR (The Campaign Registry), which acts as the central record-keeper for all 10DLC submissions. You tell TCR who you are and what you're sending. In return, carriers treat your messages as legitimate traffic. The distinction TCR polices is A2P versus P2P (Person-to-Person): a person texting a friend needs no registration, while software texting customers does, even at a small volume of appointment reminders. Virtually all messages sent through a platform like Sent are A2P.

TCR plays the same role for US SMS that Meta's Business Verification plays for WhatsApp: an identity layer that lets the network attach a reputation to a sender. The difference is that 10DLC is carrier-imposed and US-specific, while WhatsApp's rules are global.

Brands and campaigns: the two halves of a registration

Every 10DLC submission has two parts, reviewed very differently.

A brand is your business identity: legal name, address, tax ID. TCR verifies your business is real using the information you provide. This review is algorithmic, fast, and mostly a lookup against existing business registration data.

A campaign describes the messages themselves: the type of messages you're sending, who's receiving them, how they opted in, and sample examples. Unlike brand verification, a campaign is manually reviewed by a human, which is where things get inconsistent. The same campaign description can pass or fail depending on who reviews it, and rejection error codes (805, 806, 851) give you a category of problem rather than specific guidance on what to fix.

This split explains most of the friction in the process. The brand check rarely fails for a real business, but campaign review is subjective, so the documented content rules (opt-in forms, autoresponses, sample messages) exist to remove any grounds a reviewer might have for rejection.

Volume tiers and trust

Campaigns are tiered by declared volume. Below 2,000 messages per day, a campaign qualifies as low volume, with lower registration fees and fewer declared use cases (up to 5, rather than 11 for a standard campaign); past that threshold it registers as standard (high volume). TCR also assigns each brand a trust score, and carriers use it to set throughput limits: a better-established brand can send faster.

Some senders register the cheapest tier or a convenient use case and plan to correct it later. This is usually counterproductive: carriers compare your registered use case against your actual traffic, and mismatches lead to filtering or campaign suspension. Registering what you actually send is the reliable path.

Where Sent fits

Sent sits between you and TCR. You fill out one form in the Sent dashboard (or submit via the API), and the Sent compliance team reviews your submission before it reaches TCR. Because campaign review is the subjective, human part, this pre-review catches the problems that commonly cause rejections. Sent then submits the registration on your behalf, tracks the review, and notifies you when you're approved or when something needs fixing.

You never interact with TCR directly, but the registration is still legally yours: TCR ties each campaign to the business responsible for the messages, which is why agencies and resellers must register each client separately rather than bundling them under one campaign.

Where to go from here

Now that you understand what 10DLC registration involves, you can act on it:

• 10DLC Registration Guide: register your brand and campaign through the Sent dashboard
• Register 10DLC Campaigns via the API: programmatic registration for agencies and resellers
• Compliance & Regulations: what Sent enforces at send time, and per-region regulations beyond the US
• Compliance & 10DLC Issues: fixes when 10DLC errors block your sending