Programmable SMS in 2026: A2P, 10DLC, and What Developers Need to Know
A practical guide to A2P 10DLC compliance, throughput limits, and sending SMS that actually gets delivered in the US.
What is A2P 10DLC?
A2P stands for Application-to-Person — sending SMS from an application (like your app's backend) to a person. 10DLC stands for 10-Digit Long Code — a standard US phone number.
Since 2021, US carriers require that all A2P SMS sent from 10-digit long codes be registered through the A2P 10DLC program. Unregistered A2P traffic is throttled, blocked, or labeled as spam.
If you're sending transactional SMS, OTP codes, appointment reminders, or marketing messages from a regular US phone number, this applies to you.
Why does this matter?
Two reasons:
- Deliverability — Unregistered traffic is heavily filtered. You might see delivery rates drop below 50% without registration.
- Throughput — Registered long codes can send up to 1 message/second. Unregistered? Often 0.1/second or blocked entirely.
The registration process
A2P 10DLC registration has two parts:
1. Brand registration
Register your company with The Campaign Registry (TCR). Requires:
- Legal business name
- EIN (US tax ID) or equivalent
- Company type (private, public, nonprofit)
- US business address
- Stock exchange/ticker (if public)
2. Campaign registration
Register your specific use case. Requires:
- Campaign type (transactional, marketing, OTP, etc.)
- Sample messages (2-5 examples)
- Opt-in/opt-out description
- Embedded links (yes/no)
- Embedded phone numbers (yes/no)
Approval typically takes 1-5 business days.
Throughput after registration
| Number Type | Throughput |
|---|---|
| Registered long code | 1 msg/sec per number |
| Toll-free (verified) | 3 msg/sec per number |
| Short code | Up to 500 msg/sec |
For most use cases, a pool of 10-20 registered long codes handles 10-20 messages per second — sufficient for most SMB use cases.
How CloudVNO handles 10DLC
CloudVNO's SMS API handles 10DLC submission on your behalf. You submit your brand and campaign details through our dashboard, we register with TCR, and your numbers are activated for A2P once approved.
We also handle opt-out management automatically — STOP replies are processed and stored, so you never accidentally message an opted-out recipient.