Our outbox provides error codes associated with each parcels. Here are some details around each error code.

• '21211' - Invalid phone number
• '21408' - Sending message to someone outside US or CA
• '21610' - Attempting to send a message to someone who has unsubscribed
• '30003' - Phone number that can't receive SMS
• '30004' - Message blocked
• '30005' - Unreachable number or may not exist
• '30006' - Landline
• '30007' - Message filtered by carriers. We've found that messages using public link shorteners like TinyUrl or Bitly, or messages that contain references to federally illegal content are almost always blocked.
• '30008' - Unknown error
• '30024' - Sent a message to a mobile number that requires pre-registration.
• '30032' - Your message content is being flagged as SPAM
• '30034' - You are sending messages to the US using a US 10DLC number that is not associated with an approved A2P 10DLC Campaign.