SMS Term
Opt-Out
A customer's request to stop receiving text messages, typically by replying STOP. Businesses must honor opt-outs immediately—it's both legally required and automatically handled by SMS platforms.
Related Terms
Unsubscribe Rate
The percentage of recipients who opt out after receiving a message. Calculated as (opt-outs ÷ delivered messages) × 100. A healthy rate is under 2%—higher suggests messaging too often or irrelevant content.
A2P (Application-to-Person)
Automated text messages sent from a software application to a customer's phone. This includes marketing campaigns, appointment reminders, and transactional alerts. A2P messaging requires carrier registration for compliance.
Campaign Registration
Registering your specific message type (marketing, alerts, etc.) with mobile carriers after brand registration. Required for A2P 10DLC compliance and determines your messaging throughput limits.