450D is a SMS 365, enterprise service status code, which indicates that the HUB Account used to send MT traffic has reached the maximum amount of messages (SMS) setting configured on the account.
Reason for a 450D response
The reason why the 450D status code is returned, and the action which should be taken, is described below:
The HUB Account used to send MT messages has contractually agreed MT Volume limits.
Contact the SMS 365, enterprise service, Account Management team.
The Account Management team will provide further information regarding this response and what action is required going forward.