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Overview

Sending SMS to US numbers requires compliance with two overlapping frameworks: TCPA (consent, opt-out, quiet hours) and A2P 10DLC (campaign registration with US carriers). Both apply regardless of where your business is located.
For 10DLC brand and campaign registration on Vobiz, see 10DLC Brands and 10DLC Campaigns. For the TCPA explainer see What Is TCPA?.
Written consent for marketing SMS requires a clear opt-in — a consumer actively agreeing to receive promotional messages from your business. Valid methods:
  • Web form opt-in with unchecked checkbox
  • Keyword opt-in (e.g., text JOIN to 56789)
  • Paper form with signature
  • Digital agreement with clear disclosure
What does not qualify: Pre-checked opt-in boxes, consent bundled into terms of service without separate disclosure, or buying a contact list (the contacts never consented to hear from your company specifically).

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A2P 10DLC registration

10DLC (10-Digit Long Code) is the US carrier framework for business SMS sent from standard 10-digit phone numbers. All A2P (application-to-person) SMS sent at scale to US numbers requires 10DLC registration. Why it exists: US carriers implemented 10DLC to combat SMS spam. Unregistered A2P traffic is filtered or blocked. Registered campaigns get higher throughput and better deliverability. What you register: Registration steps on Vobiz:
  1. Register your brand — business details, tax ID
  2. Create a campaign — select use case, provide message samples
  3. Assign your Vobiz US numbers to the campaign
  4. Carriers approve (typically 24–72 hours); throughput unlocked
10DLC throughput by use case: Unregistered long-code traffic is typically capped at 1 MPS and subject to filtering.

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Toll-free numbers — alternative to 10DLC

US toll-free numbers (800, 888, 877, 866, 855, 844, 833) have their own verification process separate from 10DLC. Toll-free verification offers:
  • Higher throughput than unverified long code
  • National reach without per-state 10DLC complexity
  • Suitable for transactional and marketing use cases
For toll-free SMS on Vobiz, see US Toll-Free SMS.

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Short codes — high-volume campaigns

US short codes (5–6 digit numbers) are provisioned directly with carriers and offer the highest throughput (100+ MPS). They require a separate provisioning process (8–12 weeks) and monthly fees. Best suited for very high-volume campaigns (10M+ messages/month).

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Quiet hours for SMS

TCPA quiet hours apply to SMS messages the same as voice calls: Sending marketing SMS outside these hours is a TCPA violation. Time zone determination must be based on the recipient’s area code.

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Opt-out requirements

US carriers enforce standard opt-out keywords automatically on 10DLC and toll-free traffic. You must also handle opt-outs at the application level: Vobiz handles STOP responses automatically — opted-out numbers are added to your suppression list and excluded from future campaign sends. Re-engagement rule: After an opt-out, you may send one confirmation SMS only. Any further messages require a new opt-in.

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US vs India SMS compliance — comparison

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Compliance checklist for US SMS on Vobiz

  • Obtain prior express written consent before any marketing SMS
  • Register brand and campaign on 10DLC before sending at scale
  • Assign sending numbers to your registered campaign
  • Include opt-out instructions in every marketing message (“Reply STOP to opt out”)
  • Honour opt-out requests immediately — Vobiz handles STOP automatically
  • Restrict sends to 8am–9pm in the recipient’s local time zone
  • Do not send to numbers on your internal suppression list
  • Scrub contacts against National DNC Registry for marketing campaigns
  • Review message content against CTIA messaging guidelines