GSM 03.40

GSM 03.40 or 3GPP TS 23.040 is a mobile telephony standard describing the format of the Transfer Protocol Data Units (TPDU) of the Short Message Transfer Protocol (SM-TP) used in the GSM networks to carry Short Messages. This format is used throughout the whole transfer of the message in the GSM mobile network. In contrast, application servers use different protocols, like Short Message Peer-to-Peer or , to exchange messages between them and the Short message service centre.

GSM 03.40 is the original name of the standard. Since 1999 it is being developed by the 3GPP under the name 3GPP TS 23.040. However, the original name is often used to refer even to the 3GPP document.

The GSM 03.40 TPDUs are used to carry messages between the Mobile Station (MS) and Mobile Switching Centre (MSC) using the Short Message Relay Protocol (SM-RP), while between MSC a Short Message Service Centre (SMSC) the TPDUs are carried as a parameter of a Mobile Application Part (MAP) package.

In emerging networks which use IP Multimedia Subsystem (IMS) are Short Messages carried in MESSAGE command of (SIP). Even in these networks an option exists which (due to compatibility reasons) defines transfer of Short Messages in the GSM 03.40 format embedded in 3GPP 24.011 as Content-Type: application/vnd.3gpp.sms.

GSM 03.40 defines 6 types of messages, which are distinguished by the message direction and the 2 least significant bits in the first octet of SM-TP message (the TP-MTI field):

SMS-SUBMIT is used to submit a short message from a mobile phone (Mobile Station, MS) to a short message service centre (SMSC, SC).

SMS-SUBMIT-REPORT is an acknowledgement to the SMS-SUBMIT; a success means that the message was stored (buffered) in the SMSC, a failure means that the message was rejected by the SMSC.

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