SMS Gateway Project

The javax.comm for Serial Communications

Yearbook Editor — Thu, 31 May 2007 08:41:31 +0000

When deciding what language to use in making the SMS Gateway, I decided to use the Java since it supports most of the functionalities I need. I am not an expert in this language. It was just last semester that I learned this language from our Computer Applications subject. Since I already know how to use MySQL in a Java Application, interfacing the SMS to Web would now be a lot easier. But again, I face the problem on how to make my Java Application talk with my phone.

Going back to what we did on my previous post, I have reduced the problem on how would my Java Application listen on COM5. I have already established the COM5 on my phone (and seen it working), well that narrows the complications of finding my solution.

Since I am aware that my application would be listening to COM5, I tried to look for an extension for my Application. I found the javax.comm Java extension publicly distributed for free by Sun Microsystems. The extension versions that I found first was for the Solaris systems (which obviously won’t work on my XP).

COMM API (javax.comm) is a Java extension providing access to RS-232 serial ports and IEEE-1284 parallel ports (SPP mode)

Trying to dig the net for a copy of a javax.comm for Windows, I found it here. It’s the version 2.0 of the COMM API made for third party environments like windows.

Learning the AT Commands

Yearbook Editor — Thu, 31 May 2007 06:59:47 +0000

AT Commands are commands used by devices equipped with modems. The AT prefix (also known as the Attention Code), signals the modem that one or more commands are to follow. These commands are industry standard language used to communicate with the modem. A modem is always either in the command mode, or the on-line mode. The modem starts up in command mode when it is first switched on. Commands are only accepted by the modem when it is in command mode. Commands input when the modem is on-line, are treated as data, not as commands. Commands may be entered from the terminal mode of most communications software packages.

Settings made via AT commands are automatically reused by the modem until another command is received to change them, or the modem is turned off.

For the project’s case, I am using a Sony Ericsson K608i which is equiped with a built-in modem which can be accessed via Bluetooth, Infrared, USB Cable or RS232 Connection. But since of availability concerns, I would be using a Bluetooth device for accessing the modem.

AT Commands for Sony Ericsson can access almost all phone services available for your mobile phone. From sending and receiving text messages to creating custom menus. All of these commands are published by Sony Ericsson in their Developer’s Guidelines for AT Command. Just to introduce some basics on how these work, a HyperTerminal in Microsoft Windows can be used to explore the built-in phone modem.
The Set-Up

Most Bluetooth devices have a capacity to create a Serial Communication Port (COM) which can be used by another Bluetooth Device to connect to the computer. By creating a COM for the mobile phone, we can easily access the modem through the program called HyperTerminal. For this case, I created reserved COM5 for my mobile phone.

Running the HyperTerminal

HyperTerminal can be accessed from Windows XP by clicking Start > All Programs > Accessories > Communications >HyperTerminal
A detailed instruction on running the HyperTerminal can be found here.

Testing AT Commands

Once the device is connected through COM5, we can now access the phone’s mode. The following command should be used in testing the working condition of the phone’s modem.

AT
OK (you should get this reply to see if the modem supports the AT Commands)
AT*
(a list of all available AT commands will appear after the return key is hit)

For a complete list of the AT Commands available for Sony Ericsson Phones, please check the Developer’s Guidelines for AT Command.

The Work Plan

Yearbook Editor — Sat, 19 May 2007 02:42:34 +0000

We should first know how the system works before we could start working on it. From this, I have designed the data flow for the SMS Gateway that I am going to make.

SMS > Phone > Bluetooth > COM > JAVA > MySQL > PHP > Web

The first stage starts when the incoming SMS Message enters the phone. The SMS Message should be delivered to the PC via bluetooth (COM). From the bluetooth device, an application would interpret the message and save the decoded message in a MySQL Database. A PHP Script would fetch messages from a MySQL Database and publish it to the Web.

Dissecting the SMS

Yearbook Editor — Thu, 17 May 2007 11:27:59 +0000

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.

Project Genesis

Yearbook Editor — Wed, 16 May 2007 14:15:26 +0000

I was asked to create a system in which a user can easily integrate GSM Communication with Web Services. The first goal is to publish content to web by sending and SMS from a mobile phone. This can be done by storing the SMS data into a MySQL Database where a web application can easily utilize such information.

I was faced with several options in giving a solution to this problem. First, is to make use of the local Service Provider’s API for such services wherein it would cost a lot and not to mention the trouble of having to sign contracts and legal papers for such service. Second is to purchase a software like Oxygen Software which can be used to access the SMS, MMS, Phonebook and other mobile phone services. But this kind of application would cost us € 500.00. The third option is to purchase a commercial SMS Gateway like Ozeki which can easily integrate SMS Functionality in several application environments.

From the third option, an idea of creating a similar application hit me. Ozeki is just a normal application which was designed to perform services of an SMS Gateway used by GSM Service Providers. If a computer can communicate with a mobile phone in realtime, every data received by the mobile phone could easily be manipulated by the computer. These data can be used in delivering services such as the SMS to Web functionality. The next problem is determining where to start.