After tyntec receives a correct submit_sm request, a submit_sm_resp will be issued. The submit_sm_resp contains the message ID in the message_id parameter, which is a unique identifier for each message. It may vary in format and length. The submission of the message to tyntec is finalized upon issuing a submit_sm_resp. The messages are stored in the tyntec SMSC and will be delivered to the receiver. If the initial delivery attempt is not successful (e.g. the receiving mobile phone is turned off), further delivery attempts will be made. The message will be kept in the tyntec SMSC for up to 72 hours, after which it will expire.