Troubleshooting SMS Delivery Failures

Possible Reasons for SMS Delivery Failures

1. At the Pest AI Layer

1. DND Enabled
   When a contact has Do Not Disturb (DND) enabled on the SMS channel, Pest AI does not send the SMS and displays an error message.

2. Landline Number Detected
   Pest AI verifies whether a contact’s phone number is SMS-capable. If the number is a landline, SMS sending will be skipped, with an error message displayed.

3. Ramped Sending for New Sub-Accounts
   New sub-accounts have gradually increased sending limits to reduce spam risk. Agencies can choose to adjust these restrictions.

4. Daily SMS Quota Exceeded
   Agencies may set daily SMS limits per sub-account. If this limit is reached, Pest AI will stop sending bulk SMS, though individual messages will still be sent for client responses.

5. SMS Sending Suspension Due to High Error or Complaint Rates
   High error, opt-out, or complaint rates can result in suspended SMS privileges to prevent spam. During this suspension period, attempted SMS messages will show an error.

2. At the Twilio/LC Phone Layer

1. Twilio DND List
   If a contact previously opted out from the Twilio number, they must opt back in by texting “START” to receive messages.

2. 30001 - Queue Overflow
   Twilio queues messages based on sending rates. Messages queued for over 4 hours automatically fail. Adjusting the Validity Period in the Messaging Service settings can help.

3. 30002 - Twilio Sub-Account Suspension
   A suspended Twilio sub-account during message processing results in failed delivery. Contact Twilio or Pest AI support for assistance.

3. At the Carrier Network Layer

1. 30003 - Unreachable Destination Handset
   Failure can occur if the handset is off, has insufficient signal, or is a landline, or due to carrier issues.

2. 30004 - Message Blocked
   Messages may be blocked if the destination is on a Do Not Call registry, has insufficient signal, or if a previous “STOP” request was issued by the user.

3. Attachment File Size Exceeded
   Large attachment sizes can cause SMS delivery to fail.

4. Geo Permission Restrictions for International SMS
   Some international messages may require specific permissions, affecting SMS delivery.

5. Message Body Character Limit Exceeded (1600 Characters)
   Messages exceeding 1600 characters will not send. Ensure no custom values like {{message.body}} are pushing the body text over the character limit.