This article describes the protocol of data exchange that is the modification of the well-known OBEX protocol used in the GSM Samsung phones from the SHP family. The described modification of this protocol lets you write data to the phone and also get and save them.

Written by:
Khrystenko Artem,
Software Developer of Device Team.

Introduction
Main protocol commands format
The sequence of commands
Commands examples
References

Introduction

This article describes the protocol of data exchange that is the modification of the well-known OBEX protocol used in the GSM Samsung phones from the SHP family. The described modification of this protocol lets you write data to the phone and also get and save them.

Samsung Corporation made the new line of phones from SHP family and implemented the support of OBEX protocol in them that had not been used in the phones of this company before. Tries to use the common OBEX protocol did not succeed. This problem was solved by means of sniffing the Samsung PC Studio 3.0 utility. The obtained results are given in the main part of the article.

This article will be useful for those who develop utilities for writing/reading information from the phones. The described protocol modification will solve the problem of communicating with the device.

First we consider three main types of the protocol commands. Then we pay our attention to the sequence of the commands sent to connect with the device, read data and finish the session. Then I will give some examples for the main commands. At the end of the article some summary will be given.

Main protocol commands format

All protocol commands can be divided into 2 types:

1. AKN-packages. They are packages to confirm the data receiving and request the next part of the extended package.
2. Data packages. They are initialization, acquiring, closing etc. There can be Request and Answer packages.

AKN package is one block with 3 bytes length: 0x83 0x00 0x03.

Request package has the following structure:

The description of the Answer packages is given in the table below.

The sequence of commands

As any standard communication protocol modified OBEX consists of the sequence of requests and answers. In general the communication session can be divided into 3 phases:

1. Initialization
2. Acquiring data
3. Closing the session

Table with the session description is given below.

Commands examples

Let’s consider some examples of the data acquisition. They will be the examples of working with the file system.

Obtaining the list of subfolders of the folder(m-obex/fs/folder_listing)

Request

     
  83 00 29  CB 00 00 00 01  42 00 1C 6D 2D 6F 62 65    ?.)E....B..m-obe
  78 2F 66  73 2F 66 6F 6C 64 65 72 5F 6C  69 73 74    x/fs/folder_list
  69 6E 67 00 01 00 05 2F 00                           ing..../.

Answer

 A0 00 FC 42 00 1B 6D 2D 6F 62 65 78 2F 66 73 2F   .uB..m-obex/fs/
 66 6F 6C 64 65 72 5F 6C 69 73 74 69 6E 67 C3 00   folder_listingA.
 00 00 D6 49 00 D9 41 75 64 69 6F 2C 30 2C 31 31   ..OI.UAudio,0,11
 31 30 30 31 30 31 30 2C 32 30 30 34 3A 30 33 3A   1001010,2004:03:
 30 31 20 30 31 3A 30 33 3A 30 30 5C 72 5C 6E 47   01 01:03:00\r\nG
 72 61 70 68 69 63 73 2C 30 2C 31 31 31 30 30 31   raphics,0,111001
 30 31 30 2C 32 30 30 34 3A 30 33 3A 30 31 20 30   010,2004:03:01 0
 31 3A 30 33 3A 30 30 5C 72 5C 6E 56 69 64 65 6F   1:03:00\r\nVideo
 2C 30 2C 31 31 31 30 30 31 30 31 30 2C 32 30 30   ,0,111001010,200
 34 3A 30 33 3A 30 31 20 30 31 3A 30 33 3A 30 30   4:03:01 01:03:00
 5C 72 5C 6E 4D 75 73 69 63 2C 30 2C 31 31 31 30   \r\nMusic,0,1110
 30 31 30 31 30 2C 32 30 30 34 3A 30 33 3A 30 31   01010,2004:03:01
 20 30 31 3A 30 33 3A 30 30 5C 72 5C 6E 4F 74 68    01:03:00\r\nOth
 65 72 20 46 69 6C 65 73 2C 30 2C 31               er Files,0,1
 31 31 30 30 31 30 31 30 2C 32 30 30 34 3A 30 33   11001010,2004:03
 3A 30 31 20 30 31 3A 30 33 3A 30 30 5C 72 5C 6E   :01 01:03:00\r\n

  

Each element of the list is the folder description: [Name][Size(always 0)][Attributes][Modified][Created].

So in the example of these two commands you can see the general structure of the package in the modified OBEX protocol.

In conclusion I want to mention that the records in the phone book as well as the calendar are represented in VCard as it was in the previous versions of the OBEX protocols.

References

http://en.wikipedia.org/wiki/VCard
http://en.wikipedia.org/wiki/ICalendar
http://www.ixbt.com/mobile/review/obex.shtml