TroubleshootingIntermediate5 min read

SMS Delivery Failing After A2P Approval? Check These Settings

Troubleshoot SMS delivery failures when A2P is already approved. Check recipient numbers, message content, and carrier filtering.

Quick Answer: If SMS fails after A2P approval, check that recipient numbers are valid mobile numbers (not landlines), verify message content doesn't trigger spam filters, and test with different recipient numbers to isolate the issue.

What You'll Learn

This guide helps troubleshoot SMS delivery issues when your A2P registration is already approved.

Common Causes of Delivery Failure

  • Invalid phone number: Number doesn't exist or is formatted wrong
  • Landline number: SMS can't be delivered to most landlines
  • Carrier filtering: Message content triggered spam detection
  • Recipient blocked: User opted out or blocked your number
  • Carrier outage: Temporary delivery issues on carrier network

Troubleshooting Steps

  1. Verify the number: Confirm the phone number is correct and is a mobile number
  2. Test with your phone: Try sending to your own verified mobile number
  3. Check message content: Remove any potentially spam-like content
  4. Try different recipient: Test with another known-good number
  5. Review AI Conversations: Check if the send attempt was logged

Content That Can Trigger Filtering

  • URLs/links (especially shortened URLs)
  • ALL CAPS text
  • Excessive punctuation (!!!, ???)
  • Certain keywords (free, prize, winner)
  • Very short messages with no context

Phone Number Validation

Ensure phone numbers are:

  • 10 digits for US numbers (or with +1 country code)
  • Actually mobile numbers (landlines can't receive SMS)
  • Not disconnected or invalid
  • Not on the Do Not Call list (for marketing)

Frequently Asked Questions

Q: How do I know if a message failed to deliver?
A: Check AI Conversations or Inbox for delivery status on sent messages.

Q: Can I include links in SMS?
A: Yes, but use your full business URL rather than shortened links, which can trigger spam filters.

Q: What if delivery fails to all numbers?
A: This might indicate an account issue - contact support to investigate.

Related Articles

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Last updated: February 1, 2025