SMS non-delivery and complaints

SMS non-delivery overview

Non-deliveries mean SMS messages aren't reaching recipients. It's important to take these issues seriously to protect the recipient's experience. Non-deliveries can also point to problems with how you send SMS, especially if there's a rise in bounces or complaints.

Avoiding non-deliveries and complaints is key for maintaining good SMS delivery rates. Too many issues can harm your reputation as a sender. Following best practices will help ensure your SMS messages reliably reach recipients.

Learn more about SMS deliverability.

Invalid SMS statuses

The following table describes the SMS status attributes for an Invalid SMS activity.

Blacklisted	This can occur due to the following reasons: Contact is unsubscribed with the SMS provider e.g. Twilio/Tall Bob. If sending is not permitted for the recipient's region. Tall Bob provider responded with "invalid sender-id". Tall Bob provider responded with one of the following 4xx http-status codes: StatusBadRequest StatusUnauthorized StatusForbidden StatusNotFound StatusMethodNotAllowed Kudosity provider responded with one of the following 4xx http-status codes: StatusBadRequest StatusUnauthorized StatusForbidden StatusNotFound StatusMethodNotAllowed
Invalid SMS status	Description
Contact not found	Contact with the ID provided for sending has not been found. Perhaps because it was recently deleted.
Contact was opted out	Contact is globally unsubscribed from SMS or is unsubscribed from SMS for the specific audience the SMS was sent to.
Duplicate	Caused by repeated attempts at triggering the same send to the same contact (i.e. a phone number that has already been sent a particular SMS). Can be the same contact record repeatedly triggering a journey that’s already been successfully triggered and delivered or due to multiple contact records with the same phone number.
Fatal-error	Kudosity provider responded with "Bad sender ID" or "Payment required".
Invalid	An internal error while getting the contact's data or failure to generate SMS text content or prepare the SMS for sending.
Invalid phone number	Either we failed to parse the contact's phone number or the provider responded with "invalid phone number". This can be caused by landline numbers or incorrect formatting of the number.
Message cannot be sent with the current combination of 'To' and/or 'From' parameters	Twilio responded that the SMS can't be sent with this combination of from/to phone numbers.
No mobile number for country	There is no phone number available for the contact’s phone number country code. Includes when international sending is enabled but this country doesn’t support international sending.
No phone numbers	Instance has no phone numbers, which is required even if using an alphanumeric Sender ID. (Except when using Tall Bob provider).
SMS blocked outside of waking hours	Tried to send SMS outside of contact's waking hours - between 8am and 9pm.
SMS prevention limit reached	The SMS limit set in your account has been reached so the recipient was not sent a particular SMS.
Temp-error	An unexpected error from the SMS provider or a sending rate limit has been reached. Suggest to wait a little bit and try sending again.
Unsupported phone number	Using Ortto’s native SMS and the recipient's phone number’s country code is not supported for sending to. Or the Phone number purchased does not support sending SMS.