What is A2P 10DLC? The Complete Guide for Developers

If you're sending SMS messages in the United States, you've probably heard about A2P 10DLC. But what exactly is it, and why does it matter for your business? This comprehensive guide covers everything developers need to know.

Understanding A2P 10DLC

A2P stands for Application-to-Person messaging. This is any SMS sent from a business application to a consumer's phone. Examples include:

Verification codes (OTP/2FA)
Order confirmations
Appointment reminders
Marketing campaigns
Notifications and alerts

10DLC stands for 10-Digit Long Code. These are standard US phone numbers with 10 digits, like (312) 555-1234. Before the 10DLC system, these numbers were primarily used for person-to-person (P2P) communication.

Why Was 10DLC Created?

In the past, businesses could send unlimited SMS messages from any phone number without oversight. This led to massive spam problems:

Unwanted marketing messages
Phishing attempts
Robocall-style text blasts
No accountability for bad actors

In 2021, the major US carriers (AT&T, T-Mobile, and Verizon) collaborated to create the 10DLC framework. The goals were:

Reduce spam - Require businesses to register and be accountable

Improve deliverability - Legitimate businesses get better throughput

Consumer protection - Give carriers tools to block bad actors

Compliance - Ensure businesses follow messaging regulations

How 10DLC Registration Works

Step 1: Brand Registration

First, you register your business (brand) with The Campaign Registry (TCR). You'll need:

Legal business name
EIN (Employer Identification Number)
Business address
Website URL
Contact information
Business type/vertical

Brand registration typically takes 1-2 business days.

Step 2: Campaign Registration

Next, you register your messaging use case (campaign). Each campaign describes:

Use case - What type of messages you're sending (2FA, marketing, notifications, etc.)
Sample messages - Examples of the content you'll send
Opt-in process - How users consent to receive messages
Opt-out process - How users can stop receiving messages (usually "Reply STOP")

Campaign registration takes 1-5 business days, depending on your use case.

Step 3: Number Assignment

Finally, you assign phone numbers to your registered campaigns. Each number can only be associated with one campaign.

Trust Scores and Throughput

After registration, your brand receives a Trust Score that determines your messaging throughput (messages per second). The scoring system:

Trust Score	Message Throughput

Low	1 msg/sec
Medium-Low	2 msg/sec
Medium	5 msg/sec
Medium-High	10 msg/sec
High	15 msg/sec

Factors Affecting Trust Score

Business age and reputation
Brand vetting (optional $40 fee for faster approval)
Use case type (2FA gets higher scores than marketing)
Historical messaging behavior

10DLC vs Short Codes vs Toll-Free

Feature	10DLC	Short Code	Toll-Free

Number format	(312) 555-1234	12345	1-800-555-1234
Setup time	1-2 weeks	8-12 weeks	1-2 weeks
Monthly cost	Low	$1,000+	Medium
Throughput	1-15 msg/sec	100+ msg/sec	3-10 msg/sec
Best for	Most use cases	High-volume campaigns	Customer support

When to Use Each

10DLC is ideal for:

Small to medium businesses
Transactional messages (OTP, confirmations)
Moderate marketing campaigns
Two-way conversations

Short Codes are better for:

Very high-volume messaging
Time-sensitive campaigns
Large enterprises with budget

Toll-Free works well for:

Customer support
Businesses wanting a 1-800 image
Lower registration requirements

What Happens Without Registration?

As of February 2025, all major US carriers block unregistered A2P traffic. If you try to send without registration:

Messages get blocked - They won't be delivered

Numbers may be suspended - Carriers can disable your number

Potential penalties - Carriers can blacklist your business

Poor deliverability - Even if some messages go through, rates are terrible

Common 10DLC Use Cases

1. Two-Factor Authentication (2FA)

typescript
import Zavudev from "@zavudev/sdk";

const client = new Zavu();

await client.messages.send({
  to: "+14155551234",
  channel: "sms",
  text: "Your verification code is 847293. Valid for 5 minutes.",
});

Campaign type: Authentication (highest throughput)

2. Order Notifications

typescript
await client.messages.send({
  to: "+14155551234",
  channel: "sms",
  text: "Your order #12345 has shipped! Track: https://track.example.com/12345",
});

Campaign type: Delivery notifications

3. Appointment Reminders

typescript
await client.messages.send({
  to: "+14155551234",
  channel: "sms",
  text: "Reminder: Your appointment is tomorrow at 2:00 PM. Reply Y to confirm or N to reschedule.",
});

Campaign type: Account notifications

4. Marketing Campaigns

typescript
await client.messages.send({
  to: "+14155551234",
  channel: "sms",
  text: "Flash sale! 20% off everything today only. Shop now: https://shop.example.com. Reply STOP to unsubscribe.",
});

Campaign type: Marketing (requires explicit opt-in)

Registration Requirements by Use Case

Use Case	Opt-in Requirement	Sample Message Needed	Approval Time

2FA/OTP	Implicit	Yes	1-2 days
Transactional	Web form/App	Yes	1-3 days
Notifications	Web form/App	Yes	2-3 days
Marketing	Double opt-in	Yes	3-5 days
Mixed	Strictest applies	Yes	3-5 days

How Zavu Simplifies 10DLC

Managing 10DLC compliance can be complex. Here's how Zavu handles it for you:

1. Automatic Registration

When you create a sender in Zavu, we automatically:

Register your brand with TCR
Create the appropriate campaign
Assign your phone numbers
Handle carrier connections

2. Included Fees

TCR charges registration fees that add up:

$4 brand registration
$15+ campaign registration
Monthly maintenance fees

With Zavu, these fees are included in your plan.

3. Compliance Monitoring

Carrier policies change frequently. We:

Monitor policy updates
Adjust your registration as needed
Alert you about required changes
Prevent compliance issues before they happen

4. Simple API

typescript
import Zavudev from "@zavudev/sdk";

const client = new Zavu();

// That's it - we handle the compliance
const result = await client.messages.send({
  to: "+14155551234",
  channel: "sms",
  text: "Your verification code is 123456",
});

console.log(result.message.id);

Common 10DLC Questions

Do I need to register if I only send a few messages?

Yes. There are no volume exemptions. Even one message per day requires registration.

Can I use my existing phone number?

Yes, as long as it's a 10-digit US number. You'll need to register it with TCR before sending.

How long does registration take?

Brand: 1-2 business days
Campaign: 1-5 business days
Total: Usually under 1 week

What if my campaign is rejected?

Common rejection reasons include:

Missing opt-out instructions in samples
Unclear use case description
Missing business information

Zavu's team reviews your registration before submission to minimize rejections.

Can I send to multiple countries?

10DLC only applies to US numbers. For international messaging, different regulations apply. Zavu handles this automatically based on the destination number.

Getting Started

Ready to start sending compliant SMS? Here's how:

Sign up for Zavu at dashboard.zavu.dev

Create a sender - We'll guide you through the registration

Install the SDK - npm install @zavudev/sdk

Send your first message - Our API handles the rest

A2P 10DLC Fees 2025 - Complete fee breakdown
10DLC Registration Requirements - Step-by-step guide
SMS API for Developers - Full API documentation

Need help with 10DLC compliance? Our team is here to help. Contact us or join our Discord community.