> 2.11 | SMS

> Figure 69: SMS
> SMS is a service to transfer short messages between a GSM MS and an SME via an SC. Siemens GSM modules support two modes: text mode and PDU mode. The minimal requirements to send a short message are:

> - | Service center address of your provider

> - | Destination address

> - | Content of your message

> To write or send short messages in text mode the ME must be configured to use text mode, and the service center address must be set. For further settings see Section 2.11.1, Section 2.11.2 and Section 2.11.4.
> Writing or sending a short message in PDU mode requires all attributes the short message to be coded in PDU. A PDU consists of the following parts:

> - | Service Center Address encodes the length of address field, the SCA type and the SCA

> - | First Octet encodes the message type indicator, reject-duplicates, more messages to send, validity period format, user data header indicator, status report request and status report indication

> - | Message Reference

> - | Destination-Address encodes the destination address, the length of destination address field and the type of destination address

> - | Protocol-Identifier

> - | DataCoding-Scheme

> - | Validity Period

> - | User-Data-Length

> - | User-Data encodes the user data header and user data

> For detailed explanation of all fields and parameters see [8].
> Figure 70: PDU example