Glossary

A2P 10DLC (Application-to-Person 10-Digit Long Code) is the US framework that governs business messaging sent from standard 10-digit phone numbers.
It requires businesses to register their brand, messaging use cases, and phone numbers to improve message deliverability, reduce spam, and comply with carrier regulations.

The Campaign Registry (TCR) is the central authority that manages A2P 10DLC brand and campaign registrations in the US.
Businesses must register their brand and messaging use cases with TCR before sending A2P messages. TCR validates business information and assigns campaign attributes used by carriers to enforce compliance.

A carrier is a telecommunications company that delivers phone calls and messages to end users.
For A2P 10DLC, carriers are responsible for enforcing registration requirements, applying messaging limits, and filtering spam or unregistered traffic.

US mobile network operators are the major wireless carriers that operate mobile networks in the United States.
They review A2P 10DLC registrations, enforce messaging policies, apply throughput limits, and decide whether messages are delivered, filtered, or blocked.

A message segment is a portion of an SMS message. Standard SMS messages have character limits, and longer messages are automatically split into multiple segments by carriers.
In A2P 10DLC, messaging fees, throughput limits, and compliance rules are often calculated per segment, not per message.

An EIN (Employer Identification Number) is a unique number issued by the US Internal Revenue Service to identify a business entity.
In A2P 10DLC registration, an EIN is commonly required to verify a business’s legal identity and improve approval chances for messaging campaigns.

OTP (One-Time Password) verification is a security step that requires receiving a one-time code on a mobile phone number.
During A2P 10DLC registration, OTP verification helps confirm that a phone number is valid, reachable, and controlled by the registering party.