Online PDU Encoder and Decoder
Posted August 8th, 2007 by thoughtworks
SMS (Short Message Service) is specified by the ETSI (standards GSM 03.401 and 03.382 ). It can contain up to 160 characters, where each character is written according to the 7-bits GSM default alphabet.[ 7 bits default table ]
SMS also contains some meta-data, e.g.
Info about the senders ( Service center number, sender number)
Protocol information (Protocol identifier, Data coding scheme)
Timestamp
There are 2 ways to receive and send SMS messages a, PDU (protocol discription unit) and Text mode. In this document we focus on PDU mode.
PDU format can be used on any encoding.
As an example:
07911326040000F0040B911346610089F600002080629 17314080CC8F71D14969741F977FD07
The above PDU string contains the message "How are you?" and was read from a Siemens C35i mobile phone.The string is built from hexadecimal-octets and semi decimal-octets. As mentioned, SMS contains metadata about itself.
We explain it using the example above:
PDU Encoder and Decoder
String sms message
Hexadecimal PDU Message
SMSC
Receiver
Alphabet Size
7816
How are you?