Binary SMS is a mechanisms of transforming a structured message typically in XML format into a compressed form to permit more efficient transfer of data using the 160 character limitation of short SMS message lengths. WBXML is a example of a binary SMS format, however Sahana might be able to define a more effective format tailored to the data schema's of the disaster management domain.

References

• http://mobiforge.com/developing/story/binary-sms-sending-rich-content-devices-using-sms
• http://www.nowsms.com/Binary Messages.htm

The data compression:

Considering the overhead of the header+footers added by compression protocols like gzip. The compression is only effective when large amounts of data is stored before being transmitted via a multi-part sms.

Since SMS does have limitations on the content body and reliability, it is important to mimic a message transport layer to permit a larger body of data to be passed effectively to the end point. Thus one message will be split into multiple SMS packets and queuing will be needed at the server end to consolidate these packets to the full message. This would require a message sequence number in the prefix of the message of the form

hash(IMEI) + message number + seq number

or

mobile number + message number + seq number

However if Caller Line Identification (CLI) can be assumed the mobile number can be omitted to provide more space for the already restricted message body. The queuing mechanism can be modelled on a light weight WS-RM.

The following is only a sample and needs to go through many iterations to determine the best use of the binary notation based on the frequency of the SMS messages.

message version / type
00
01
02

reference modules
10 - mpr
11 - dvr
12 - cr
..

data (e.g.)
30 - person name
31 - organisation name
32 - lat long