Dissecting the SMS
Where to start? The source. Since this project primarily deals with Short Message Service (SMS), it is a must that we should learn what makes up an SMS.
According to the European Telecommunications Standards Insitute (documented as GSM 3.40 and 3.38), an SMS Message can be up to 160 characters in length, where each character is 7 bits according to the 7-bit default alphabet.
There are two ways of sending and receiving SMS messages, either by text mode or by PDU (protocol description unit) mode. The text mode, which is not supported by most phones, is a stream of bits represented by the PDU mode. Along with the messages sent or received are meta information needed by the source and destination in processing and interpreting the messages sent and received. Meta information such as the sender’s mobile number, sms center number, timestamp, etc are contained in a part of the PDU bit stream.
More information about SMS and PDU format is provided here.
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Tagged with: SMS Project
