Diagnostic Steps
1. Check Delivery Status
Review delivery receipts from your SMS provider:
- Delivered — Message reached the carrier
- Failed — Explicit failure with error code
- Unknown/Pending — May have been filtered silently
2. Validate the Number
Check the recipient number:
- Format — Correct country code and length?
- Line type — Is it SMS-capable (wireless)?
- Status — Is the number active?
Validate numbers. Check line type and carrier status instantly.
Get Free API Key3. Review Your Registration
- Is your 10DLC registration complete and approved?
- Is the sending number associated with a campaign?
- Does your content match registered use cases?
4. Examine Message Content
- Any spam trigger words?
- Using URL shorteners?
- ALL CAPS or excessive punctuation?
Common Issues and Solutions
| Issue | Likely Cause | Solution |
|---|---|---|
| No delivery receipt | Filtered by carrier | Check 10DLC registration; review content |
| Error: Invalid number | Number doesn't exist | Validate numbers before sending |
| Error: Unreachable | Phone off or no service | Retry later; remove after multiple failures |
| Delivered but not received | Phone-level spam filter | Contact from known number first |
| Very slow delivery | Routing congestion | Check carrier-specific routes |
Carrier-Specific Issues
If issues only affect certain carriers:
- Check for carrier-specific filtering rules
- Verify your 10DLC is approved with that carrier
- Consider alternative routing paths
- Contact your SMS provider for carrier-specific support
When to Escalate
Contact your SMS provider if:
- Issues persist after fixing content and registration
- Delivery rates suddenly drop across all carriers
- You receive carrier block notifications
- Error codes don't match documented issues