PDU SMS format

PDU SMS Format

Terms:

SC – Service Center

MS – Mobile Station

SME -- Short Message Entity, entity which may send or receive Short Messages

ME -- Mobile Equipment

The SMS protocol stack is composed of four layers: the application layer, the transfer layer,the relay layer and the link layer.

The application layer(SM-AL) is implemented in SMEs in the form of software applications that send, receive and interpret the content of messages (e.g. message editor, games, etc.).

At the transfer layer(SM-TL), the message is considered as a sequence of octets containing information such as message length, message originator or recipient, date of reception.

At the transfer layer, the message is delivered in the form of a PDU of type SMS-DELIVER. The PDU can contain several of the following parameters:

- Message type (SMS-DELIVER)

- Indication that there are more messages to be received

- Request for reply path

- Request for a status report

- Address of the originator SME

- Protocol identifier

- Data coding scheme

- Service centre time stamp (time at which the SM-SC received the message)

- User data header

- User data (with associated length).

Here is a example. There are 38 octets in this sample message. The PDU string consists of the following:

25 04 81 31 09 10 40 0B 81 31 06 97 80 93 F3 00 00 70 20 62 58 81 82 00 0E 04 01 02 87 01 C4 64 33 5A 58 3C 26 03