Common delivery error codes

If a message fails, the log will show a numeric error code. Here are the most common ones and what they mean.

4452 — Message queue timeout

•The message expired before delivery

•Usually transient; resend if urgent

4720 — Carrier rejected the message

•The recipient's carrier refused the message

•Check if the number is valid; may indicate a deliverability issue with your campaign

4750 — Rate limited

•You're sending faster than your account is allowed

•Slow down or contact support to request a higher rate

4780 — Daily brand cap exceeded

•You've hit your daily message limit for that carrier

•See our article on daily message limits

9902 / 902 — Handset or network block

•The recipient's device or network is blocking your number specifically

•Could be individual block or a broader reputation issue

If you see these repeatedly

Contact support. Persistent errors often indicate a registration or deliverability issue we can fix.