If a message you sent is not delivered to the end device and returns a 30008 error code, this means that delivery of your message failed for unknown reasons.
When Medallia Concierge receives a very generic error from our carrier partner that we have no further details about, we associate the message with the error code 30008, letting you know that Medallia Concierge truly doesn't know what caused this error from the provider.
Possible Solutions
Ensure that the phone is not roaming off network. We cannot guarantee message delivery on roaming phones.
Try sending to other phones who have the same mobile carrier (you can use our Lookups API to determine the carrier if you're unsure). If messages to other phones go through, the issue is likely device related. Try rebooting the device or contact the mobile carrier for help.
If you are sending SMS from an alphanumeric sender ID, see if using a Medallia Concierge phone number works better. We've observed that certain networks may block alpha sender IDs.
Try sending a shorter message to the phone, with simple content that does not include any special characters. This would give our support team an idea as to whether the failure is related to concatenation or character encoding.
Medallia Concierge support can help investigate what went wrong with our carriers. Please open a support request and include a minimum of 3 or more instances where a 30008 error was thrown. Per our carriers' requirements, these messages can be no older than 48 hours at most.