A2P 10DLC Explained: How to Send Compliant SMS Marketing in 2026

A2P 10DLC — Application-to-Person 10-Digit Long Code — is the carrier-approved standard for businesses sending text messages to customers from a standard local 10-digit phone number. It replaced the old short-code system and is now the only way to send SMS marketing, appointment reminders, and Google review requests legally and reliably.

Why Unregistered Texts Get Blocked

The major cellular carriers (AT&T, T-Mobile, Verizon) now require every business that sends A2P messages to register its brand and campaign use case through The Campaign Registry (TCR). Texts from unregistered numbers get filtered, throttled, or blocked entirely. Carriers do this to fight spam — and it means any business texting without A2P 10DLC registration is flying blind, with messages silently never arriving.

• Unregistered SMS is increasingly blocked or filtered by carriers
• Registration proves you're a legitimate, vetted business — not spam
• Registered brands get far higher send throughput and delivery rates
• Campaign use cases (marketing, reminders, reviews) must be declared

The Compliance Checklist That Matters

Compliant SMS marketing isn't just about registration. It requires proper opt-in consent capture (the A2P authorization checkbox), STOP/HELP keyword handling, identifiable sender information, and respect for message frequency and quiet hours. Get any of these wrong and you risk carrier penalties — or worse, FCC-level violations under the TCPA.

Consent isn't a checkbox you add at the end — it's the legal foundation that lets you reach 98% of your customers on the channel they actually open.

Why the ROI Justifies the Setup

SMS marketing has a 98% open rate — far above email — and about 90% of texts are read within three minutes. For Los Angeles, CA businesses, that makes compliant SMS one of the highest-ROI channels available: time-sensitive promotions, appointment reminders that slash no-shows, and automated Google review requests that grow your Map Pack authority. IntelliSitez handles the full A2P 10DLC registration, brand vetting, and campaign setup — then builds SMS directly into your website with proper opt-in consent, so you send legally and the messages actually arrive.