User manual

MPTP | MPTP commands 17
The exact meaning of each field, along with the typical actions taken on reception of the message, is given
for each command in this document.
3.3. Reassembling a received MPTP command
An instrument receiving an MPTP command in several parts needs to store the parts in a buffer until all of
them have been received. As soon as the full set (01/NN, 02/NN, , NN/NN) is present, the command
can be reassembled and processed.
Please note that depending on the GSM network used, the parts may not always arrive in the order in
which they were sent. Moreover, some GSM networks may cause delays in delivering some parts, and
losing parts altogether is not unheard of. These things are caused by the GSM network used and affect all
short messages, not only MPTP messages. However, they need to be taken into account when
reassembling the command.
TWIG instruments feature an internal buffer for storing the parts of an MPTP command and automatically
perform the reassembly as soon as all parts have been received. Receiving another command of the
same type clears the previous parts from the buffer.
3.4. Encryption
The TWIG Message Encryption System is a solution for securing SMS communication. The system
provides secure end-to-end data transmission for SMS and location and telematics messages, and makes
it virtually impossible to obtain message unauthorised. The encryption also enables the secure
identification and authentication of the message sender.
Cf. Benefon message encryption system.pdf for detailed information about the solution.
3.5. Transliteration
Some of the TWIG terminals support UCS2 characters in the user interface and with this support
messages can be written also with Cyrillic, Greek and Hebrew characters. As already mentioned earlier
MPTP messages use the 7-bit GSM character set. This set does not include the Cyrillic, Greek or Hebrew
characters, so for example status messages written with Cyrillic characters cannot be used if
transliteration is not done.
All user editable strings which are added to MPTP messages are transliterated before sending the
message. For Cyrillic and Greek characters standard transliteration is done. Hebrew characters are
mapped one to one to small Latin characters and all Latin characters are written with capital letters (if
Hebrew is used).
3.6. Base64 encoding
Base64 encoding is used for converting 8-bit binary data blocks into 7-bit GSM characters. By doing this
normal 7-bit SMS can be used for sending and receiving more data than if it would be in the normal semi-
readable format.
Full specification for the Base64 Content-Transfer-Encoding can be found at
http://www.funet.fi/pub/doc/rfc/rfc1521.txt