Why did my SMS fail to deliver?
Understand the different SMS statuses and common reasons for delivery failures.
SMS statuses explained
Each SMS in a campaign goes through several statuses:
- Queued: waiting to be sent
- Sending: handed to the SMS network
- Delivered: successfully received by the phone
- Failed: could not be delivered
- Rejected: blocked before sending (invalid number, opted out, etc.)
Common reasons for failed SMS
Invalid phone number
The number format is incorrect or the number does not exist. Brave Tools validates numbers before sending, so contacts with invalid or missing phone numbers are automatically excluded.
Contact opted out
The recipient clicked the unsubscribe link in a previous SMS. They are added to the opt-out list and will not receive future messages from the same sender.
Phone turned off or out of coverage
The operator tried to deliver but the phone was unreachable. The SMS is typically retried for 24 to 72 hours before failing.
Blocked by operator
Some networks block SMS from unknown senders, especially alphanumeric sender names in certain countries. This is more common in North America than Europe.
Insufficient credits
If credits run out mid-campaign, remaining messages are not sent. Check your credit balance before starting large campaigns.
How to investigate delivery issues
- Go to SMS Campaigns and open the affected campaign
- Look at the delivery breakdown (sent, delivered, failed)
- Check the failure reasons if shown
- For BYOK users: check your 46elks dashboard for detailed delivery logs
What to do next
- Verify phone numbers are in international format (+country code)
- Check your credit balance
- For alphanumeric senders: test with a phone number sender in countries where alphanumeric is blocked
- Review your sender reputation if you see high failure rates