| The SMS Gateway is a carrier strength proprietary send sms messaging platform and set of development tools that enables intelligent delivery and routing of SMS messages between multiple networks. It acts as a bridge between carriers and mobile services providers residing on various and otherwise disconnected networks (for example the Internet and various wireless networks SMPP,CIMD). The Wire2Air SMS Gateway is a messaging application and Internet server that exposes a set of API calls and HTTP interfaces and enables our partners and customers to quickly develop mobile messaging applications for their particular need and business. Wire2Air SMS Gateway can manage simultaneous connections to one or more SMSCs, supporting the major SMSC protocols, including SMPP, UCP/EMI, CIMD2, and/or HTTP. Wire2Air SMS Gateway handles the low level protocol details, and makes it easy to switch between different providers, as well as making it easy to add additional connections for situations where it is advantageous to route messages for different countries via different providers. 2-Way Interactive SMS Gateway Application- Wire2Air SMS Gateway is a great tool for enabling rapid development of interactive SMS applications and services. When Wire2Air SMS Gateway receives an SMS message, it can be configured to dispatch that message to a script running on an HTTP server, to a local executable program, or local script or batch file. This provides a simple way to get received messages into an application, so that the application can perform custom processing on the message. The application can generate a simple reply back to the received message, or perform more advanced application specific logic. Supported Message Types
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sms gateway connectivity diagram |
Wire2Air SMS Gateway functions as an email gateway for you to send SMS like you send email. The concept of a gateway allows multiple client to connect to a central server in order to send SMS  |
Tuesday, December 22, 2009
Mobile/SMS Marketing Solutions
The Procedure for Sending AT Commands to a Mobile Phone or GSM/GPRS Modem Using MS HyperTerminal(Contd...)
- The Properties dialog box comes out. Enter the correct port settings for your mobile phone or GSM/GPRS modem. Then click the OK button.
(To find the correct port settings that should be used with your mobile phone or GSM/GPRS modem, one way is to consult the manual of your mobile phone or GSM/GPRS modem. Another way is to check the port settings used by the wireless modem driver that you installed earlier.
To check the port settings used by the wireless modem driver on Windows 98, follow these steps:
a. Go to Control Panel -> Modem.
b. Select your mobile phone or GSM/GPRS modem in the list box.
c. Click the Properties button.
d. The Properties dialog box appears. The Maximum speeds field on the General tab corresponds to HyperTerminal's Bits per second field. Click the Connection tab and you can find the settings for data bits, parity and stop bits. Click the Advanced button and you can find the setting for flow control.
To check the port settings used by the wireless modem driver on Windows 2000 and Windows XP, follow these steps:
a. Go to Control Panel -> Phone and Modem Options -> Modems tab.
b. Select your mobile phone or GSM/GPRS modem in the list box.
c. Click the Properties button.
d. The Properties dialog box appears. Click the Advanced tab and then click the Change Default Preferences button.
e. The Change Default Preferences dialog box appears. The Port speed field on the General tab corresponds to HyperTerminal's Bits per second field. You can also find the setting for flow control on the General tab. On the Advanced tab, you can find the settings for data bits, parity and stop bits.)
- Type "AT" in the main window. A response "OK" should be returned from the mobile phone or GSM/GPRS modem.
Type "AT+CPIN?" in the main window. The AT command "AT+CPIN?" is used to query whether the mobile phone or GSM/GPRS modem is waiting for a PIN (personal identification number, i.e. password). If the response is "+CPIN: READY", it means the SIM card does not require a PIN and it is ready for use. If your SIM card requires a PIN, you need to set the PIN with the AT command "AT+CPIN=". 
If you get the responses above, your mobile phone or GSM/GPRS modem is working properly. You can start typing your own AT commands to control the mobile phone or GSM/GPRS modem.Further details about how to use AT commands to send and receive SMS messages will be provided in the following sections.
The Procedure for Sending AT Commands to a Mobile Phone or GSM/GPRS Modem Using MS HyperTerminal
To use MS HyperTerminal to send AT commands to your mobile phone or GSM/GPRS modem, you can follow the procedure below:
- Put a valid SIM card into the mobile phone or GSM/GPRS modem. You can obtain a SIM card by subscribing to the GSM service of a wireless network operator.
- Connect your mobile phone or GSM/GPRS modem to a computer and set up the corresponding wireless modem driver. You should find the wireless modem driver in the CD or disk that was provided by the manufacturer. If the manufacturer does not provide such CD or disk with your mobile phone or GSM/GPRS modem, you can go to the manufacturer's web site and see whether the wireless modem driver can be downloaded there. If the wireless modem driver cannot be found on the web site, you can still use Windows' standard modem driver.
- Run MS HyperTerminal by selecting Start -> Programs -> Accessories -> Communications ->HyperTerminal.
- In the Connection Description dialog box, enter a name and choose an icon you like for the connection. Then click the OK button.
- In the Connect To dialog box, choose the COM port that your mobile phone or GSM/GPRS modem is connecting to in the Connect using combo box. For example, choose COM1 if your mobile phone or GSM/GPRS modem is connecting to the COM1 port. Then click the OK button.
(Sometimes there will have more than one COM port in the Connect using combo box. To know which COM port is used by your mobile phone or GSM/GPRS modem, follow the procedure below:
In Windows 98:
Go to Control Panel -> Modem. Then click the Diagnostics tab. In the list box, you can see which COM port the mobile phone or GSM/GPRS modem is connected to.
In Windows 2000 and Windows XP:
Go to Control Panel -> Phone and Modem Options. Then click the Modems tab. In the list box, you can see which COM port the mobile phone or GSM/GPRS modem is connected to.)
How to Use Microsoft HyperTerminal to Send AT Commands to a Mobile Phone or GSM/GPRS Modem?
Microsoft HyperTerminal is a small program that comes with Microsoft Windows. You can use it to send AT commands to your mobile phone or GSM/GPRS modem. It can be found at Start -> Programs ->Accessories -> Communications -> HyperTerminal. If you cannot find it and you are using Windows 98, then probably you have not installed it. You can go to Control Panel -> Add/Remove Programs ->Windows Setup tab -> Communications list box item -> Details button to install MS HyperTerminal.
Before you start programming your SMS application, you may want to check if your mobile phone, GSM/GPRS modem and SIM card are working properly first. The MS HyperTerminal is a handy tool when it comes to testing your GSM devices. It is a good idea to test your GSM devices beforehand. When a problem occurs, sometimes it is difficult to tell what causes the problem. The cause can be your program, the GSM device or the SIM card. If you test your GSM device and SIM card with MS HyperTerminal and they operate properly, then it is very likely that the problem is caused by your program.
For Linux users, minicom can be used instead of HyperTerminal.
What is a GPRS Modem?
A GPRS modem is a GSM modem that additionally supports the GPRS technology for data transmission. GPRS stands for General Packet Radio Service. It is a packet-switched technology that is an extension of GSM. (GSM is a circuit-switched technology.) A key advantage of GPRS over GSM is that GPRS has a higher data transmission speed.
GPRS can be used as the bearer of SMS. If SMS over GPRS is used, an SMS transmission speed of about 30 SMS messages per minute may be achieved. This is much faster than using the ordinary SMS over GSM, whose SMS transmission speed is about 6 to 10 SMS messages per minute. A GPRS modem is needed to send and receive SMS over GPRS. Note that some wireless carriers do not support the sending and receiving of SMS over GPRS.
If you need to send or receive MMS messages, a GPRS modem is typically needed.
Which is Better: Mobile Phone or GSM / GPRS Modem?
In general, a GSM/GPRS modem is recommended for use with a computer to send and receive messages. This is because some mobile phones have certain limitations comparing to GSM/GPRS modems. Some of the limitations are described below:
- Some mobile phone models (example: Ericsson R380) cannot be used with a computer to receive concatenated SMS messages.
What is a concatenated SMS message?
A concatenated SMS message is a message that contains more than 140 bytes. (A normal SMS message can only contain at most 140 bytes.) Concatenated SMS works like this: the sender's mobile device breaks a message longer than 140 bytes into smaller parts. Each of these parts are then fitted in a single SMS message and sent to the recipient. When these SMS messages reach the destination, the recipient's mobile device will combine them back to one message.
What is the cause of the problem?
When the mobile phone receives the SMS messages that are parts of a concatenated SMS message, it combines them to one message automatically. The correct behavior should be: when the mobile phone receives the SMS messages that are parts of a concatenated SMS message, it forwards them to the computer without combining them. - Many mobile phone models cannot be used with a computer to receive MMS messages. Because when they receive a MMS notification, they handle it automatically instead of forwarding it to the computer.
- A mobile phone may not support some AT commands, command parameters and parameter values. For example, some mobile phones do not support the sending and receiving of SMS messages in text mode. So, the AT command "AT+CMGF=1" (it instructs the mobile phone to use text mode) will cause an error message to be returned. Usually GSM/GPRS modems support a more complete set of AT commands than mobile phones.
- Most SMS messaging applications have to be available 24 hours a day. (For example, an SMS messaging application that provides ringtone downloading service should be running all the time so that a user can download ringtones any time he/she wants.) If such SMS messaging applications use mobile phones to send and receive SMS messages, the mobile phones have to be switched on all the time. However, some mobile phone models cannot operate with the battery removed even when an AC adaptor is connected, which means the battery will be charged 24 hours a day.
Besides the above issues, mobile phones and GSM/GPRS modems are more or less the same for sending and receiving SMS messages from a computer. Actually, you can consider an AT-command-enabled mobile phone as "GSM/GPRS modem + keypad + display + ...".
There is not much difference between mobile phones and GSM/GPRS modems in terms of SMS transmission rate, since the determining factor for the SMS transmission rate is the wireless network.
ntroduction to GSM / GPRS Wireless Modems
A GSM modem is a wireless modem that works with a GSM wireless network. A wireless modem behaves like a dial-up modem. The main difference between them is that a dial-up modem sends and receives data through a fixed telephone line while a wireless modem sends and receives data through radio waves.
A GSM modem can be an external device or a PC Card / PCMCIA Card. Typically, an external GSM modem is connected to a computer through a serial cable or a USB cable. A GSM modem in the form of a PC Card / PCMCIA Card is designed for use with a laptop computer. It should be inserted into one of the PC Card / PCMCIA Card slots of a laptop computer.
Like a GSM mobile phone, a GSM modem requires a SIM card from a wireless carrier in order to operate.
As mentioned in earlier sections of this SMS tutorial, computers use AT commands to control modems. Both GSM modems and dial-up modems support a common set of standard AT commands. You can use a GSM modem just like a dial-up modem.
In addition to the standard AT commands, GSM modems support an extended set of AT commands. These extended AT commands are defined in the GSM standards. With the extended AT commands, you can do things like:
- Reading, writing and deleting SMS messages.
- Sending SMS messages.
- Monitoring the signal strength.
- Monitoring the charging status and charge level of the battery.
- Reading, writing and searching phone book entries.
The number of SMS messages that can be processed by a GSM modem per minute is very low -- only about six to ten SMS messages per minute.
How to Send SMS Messages from a Computer / PC ? (Contd)
Here is a description of what is done in the above example:
- Line 1: "AT" is sent to the GSM / GPRS modem to test the connection. The GSM / GPRS modem sends back the result code "OK" (line 2), which means the connection between the HyperTerminal program and the GSM / GPRS modem works fine.
- Line 3: The AT command +CMGF is used to instruct the GSM / GPRS modem to operate in SMS text mode. The result code "OK" is returned (line 4), which indicates the command line "AT+CMGF=1" has been executed successfully. If the result code "ERROR" is returned, it is likely that the GSM / GPRS modem does not support the SMS text mode. To confirm, type "AT+CMGF=?" in the HyperTerminal program. If the response is "+CMGF: (0,1)" (0=PDU mode and 1=text mode), then SMS text mode is supported. If the response is "+CMGF: (0)", then SMS text mode is not supported.
- Line 5 and 6: The AT command +CMGW is used to write an SMS text message to the message storage of the GSM / GPRS modem. "+85291234567" is the recipient mobile phone number. After typing the recipient mobile phone number, you should press the Enter button of the keyboard. The GSM / GPRS modem will then return a prompt "> " and you can start typing the SMS text message "A simple demo of SMS text messaging.". When finished, press Ctrl+z of the keyboard.
- Line 7: "+CMGW: 1" tells us that the index assigned to the SMS text message is 1. It indicates the location of the SMS text message in the message storage.
- Line 9: The result code "OK" indicates the execution of the AT command +CMGW is successful.
- Line 10: The AT command +CMSS is used to send the SMS text message from the message storage of the GSM / GPRS modem. "1" is the index of the SMS text message obtained from line 7.
- Line 11: "+CMSS: 20" tells us that the reference number assigned to the SMS text message is 20.
- Line 13: The result code "OK" indicates the execution of the AT command +CMSS is successful.
To send SMS messages from an application, you have to write the source code for connecting to and sending AT commands to the mobile phone or GSM/GPRS modem, just like what a terminal program does. You can write the source code in C, C++, Java, Visual Basic, Delphi or other programming languages you like. However, writing your own code has a few disadvantages:
- You have to learn how to use AT commands.
- You have to learn how to compose the bits and bytes of an SMS message. For example, to specify the character encoding (e.g. 7-bit encoding and 16-bit Unicode encoding) of an SMS message, you need to know which bits in the message header should be modified and what value should be assigned.
- Sending SMS messages with a mobile phone or GSM/GPRS modem has a drawback -- the SMS transmission speed is low. As your SMS messaging application becomes more popular, it has to handle a larger amount of SMS traffic and finally the mobile phone or GSM/GPRS modem will not be able to take the load. To obtain a high SMS transmission speed, a direct connection to an SMSC or SMS gateway of a wireless carrier or SMS service provider is needed. However, AT commands are not used for communicating with an SMS center or SMS gateway. This means your have to make a big change to your SMS messaging application in order to move from a wireless-modem-based solution to a SMSC-based solution.
In most cases, instead of writing your own code for interacting with the mobile phone or GSM/GPRS modem via AT commands, a better solution is to use a high-level SMS messaging API (Application programming interface) / SDK (Software development kit) / library. The API / SDK / library encapsulates the low-level details. So, an SMS application developer does not need to know AT commands and the composition of SMS messages in the bit-level. Some SMS messaging APIs / SDKs / libraries support SMSC protocols in addition to AT commands. To move from a wireless-modem-based SMS solution to a SMSC-based SMS solution, usually you just need to modify a configuration file / property file or make a few changes to your SMS messaging application's source code.
The links to some open source and free SMS messaging libraries can be found in the article "Free Libraries/Tools for Sending/Receiving SMS with a Computer".
Another way to hide the low-level AT command layer is to place an SMS gateway between the SMS messaging application and the mobile phone or GSM/GPRS modem. (This has been described in the section "What is an SMS Gateway?" earlier.) Simple protocols such as HTTP / HTTPS can then be used for sending SMS messages in the application. If an SMSC protocol (e.g. SMPP, CIMD, etc) is used for communicating with the SMS gateway instead of HTTP / HTTPS, an SMS messaging API / SDK / library can be very helpful to you since it encapsulates the SMSC protocol's details.
Usually a list of supported / unsupported mobile phones or wireless modems is provided on the web site of an SMS messaging API / SDK / library or an SMS gateway software package. Remember to check the list if you are going to use an SMS messaging API / SDK / library or an SMS gateway software package.
How to Send SMS Messages from a Computer / PC ?
n general, there are two ways to send SMS messages from a computer / PC to a mobile phone:
- Connect a mobile phone or GSM/GPRS modem to a computer / PC. Then use the computer / PC and AT commands to instruct the mobile phone or GSM/GPRS modem to send SMS messages.
- Connect the computer / PC to the SMS center (SMSC) or SMS gateway of a wireless carrier or SMS service provider. Then send SMS messages using a protocol / interface supported by the SMSC or SMS gateway.
The 1st Way: Sending SMS Messages from a Computer Using a Mobile Phone or GSM/GPRS Modem
The SMS specification has defined a way for a computer to send SMS messages through a mobile phone or GSM/GPRS modem. A GSM/GPRS modem is a wireless modem that works with GSM/GPRS wireless networks. A wireless modem is similar to a dial-up modem. The main difference is that a wireless modem transmits data through a wireless network whereas a dial-up modem transmits data through a copper telephone line. More information about GSM/GPRS modems will be provided in the section "Introduction to GSM / GPRS Wireless Modems". Most mobile phones can be used as a wireless modem. However, some mobile phones have certain limitations comparing to GSM/GPRS modems. This will be discussed in the section "Which is Better: Mobile Phone or GSM / GPRS Modem" later.
To send SMS messages, first place a valid SIM card from a wireless carrier into a mobile phone or GSM/GPRS modem, which is then connected to a computer. There are several ways to connect a mobile phone or GSM/GPRS modem to a computer. For example, they can be connected through a serial cable, a USB cable, a Bluetooth link or an infrared link. The actual way to use depends on the capability of the mobile phone or GSM/GPRS modem. For example, if a mobile phone does not support Bluetooth, it cannot connect to the computer through a Bluetooth link.
After connecting a mobile phone or GSM/GPRS modem to a computer, you can control the mobile phone or GSM/GPRS modem by sending instructions to it. The instructions used for controlling the mobile phone or GSM/GPRS modem are called AT commands. (AT commands are also used to control dial-up modems for wired telephone system.) Dial-up modems, mobile phones and GSM/GPRS modems support a common set of standard AT commands. In addition to this common set of standard AT commands, mobile phones and GSM/GPRS modems support an extended set of AT commands. One use of the extended AT commands is to control the sending and receiving of SMS messages.
The following table lists the AT commands that are related to the writing and sending of SMS messages:
AT command
Meaning
+CMGS
Send message
+CMSS
Send message from storage
+CMGW
Write message to memory
+CMGD
Delete message
+CMGC
Send command
+CMMS
More messages to send
One way to send AT commands to a mobile phone or GSM/GPRS modem is to use a terminal program. A terminal program's function is like this: It sends the characters you typed to the mobile phone or GSM/GPRS modem. It then displays the response it receives from the mobile phone or GSM/GPRS modem on the screen. The terminal program on Microsoft Windows is called HyperTerminal. More details about the use of Microsoft HyperTerminal can be found in the "How to Use Microsoft HyperTerminal to Send AT Commands to a Mobile Phone or GSM/GPRS Modem" section of this SMS tutorial.
Below shows a simple example that demonstrates how to use AT commands and the HyperTerminal program of Microsoft Windows to send an SMS text message. The lines in bold type are the command lines that should be entered in HyperTerminal. The other lines are responses returned from the GSM / GPRS modem or mobile phone.
AT
OK
AT+CMGF=1
OK
AT+CMGW="+85291234567"
> A simple demo of SMS text messaging.
+CMGW: 1
OK
AT+CMSS=1
+CMSS: 20
OK
What is an SMS Gateway?
One problem of SMS messaging is that SMSCs developed by different companies use their own communication protocol and most of these protocols are proprietary. For example, Nokia has an SMSC protocol called CIMD whereas another SMSC vendor, CMG, has an SMSC protocol called EMI. We cannot connect two SMSCs if they do not support a common SMSC protocol. To deal with this problem, an SMS gateway is placed between two SMSCs. This is illustrated in the following figure. The SMS gateway acts as a relay between the two SMSCs. It translates one SMSC protocol to another one. This way can be used by two different wireless carriers to interconnect their SMSCs for purposes such as enabling the exchange of inter-operator SMS messages.
Besides wireless carriers, content providers and SMS application developers may also find an SMS gateway useful. Let's consider the following situation. Suppose you are the developer of an SMS text messaging application. To send and receive SMS text messages on your server, one way is to connect to the SMSCs of the wireless carriers. Different wireless carriers may use SMSCs from different vendors, which means your SMS text messaging application may need to support multiple SMSC-specific protocols. (This is illustrated in the following figure). As a result, the SMS text messaging application's complexity and development time increases.
To deal with the above problem, an SMS gateway can be set up to handle the connections to the SMSCs. Now the SMS text messaging application only needs to know how to connect to the SMS gateway. To support more SMSCs, you just need to modify the settings of the SMS gateway. No change to the source code of the SMS text messaging application is required. The use of an SMS gateway can greatly shorten the SMS text messaging application's development time.
To connect to an SMS gateway, you can use an SMSC protocol such as SMPP and CIMD. Some SMS gateways support an HTTP / HTTPS interface. HTTP / HTTPS is easier to use than SMSC protocols. The drawback is that there may be fewer SMS features to use. For example, an SMS gateway may not support the sending of picture messages through the HTTP / HTTPS interface.
Besides using a direct connection to the SMSC of a wireless carrier, another way to send and receive SMS text messages on a computer is to use a mobile phone or GSM/GPRS modem. To do this, your SMS text messaging application has to know how to communicate with the mobile phone or GSM/GPRS modem using AT commands.
Some SMS gateways are capable of handling the connections to mobile phones and GSM/GPRS modems. To send and receive SMS text messages with a mobile phone or GSM/GPRS modem, the SMS text messaging application only needs to know how to talk to the SMS gateway and does not need to know anything about AT commands. More details about GSM/GPRS modems and AT commands will be provided in later sections of this SMS tutorial.
Open Source and Free SMS Gateway Software
As you can see in the above sections, an SMS gateway has a lot of responsibilities in an SMS messaging system. So, SMS gateway software can be very complex and complex software is usually expensive. Fortunately, there are open source SMS gateway software packages that can be downloaded free of charge over the web. One high-quality free SMS gateway software package is Kannel, which is written in the C programming language. Kannel can handle connections to SMSCs, mobile phones and GSM/GPRS modems. It has an HTTP / HTTPS interface for the sending and receiving of SMS messages.More information about Kannel can be found on its web site http://www.kannel.org/
International SMS Messages
Inter-operator SMS messages can be further divided into two categories -- local inter-operator SMS messages and international inter-operator SMS messages (international SMS messages). A local inter-operator SMS message is an SMS message that is sent from one wireless network operator to another wireless network operator in the same country, while an international SMS message is an SMS message that is sent from a wireless network operator in one country to a wireless network operator in another country.
Usually the cost for sending an international SMS message from a mobile phone is higher than that for sending a local inter-operator SMS message. Hence, the cost for sending an intra-operator SMS message <= the cost for sending a local inter-operator SMS message <= the cost for sending an international SMS message.
The interoperability of SMS messaging between two wireless networks locally and even internationally is undoubtedly a main factor that contributes to the success of SMS worldwide.
What is an SMS Center / SMSC
An SMS center (SMSC) is responsible for handling the SMS operations of a wireless network. When an SMS message is sent from a mobile phone, it will reach an SMS center first. The SMS center then forwards the SMS message towards the destination. An SMS message may need to pass through more than one network entity (e.g. SMSC and SMS gateway) before reaching the destination. The main duty of an SMSC is to route SMS messages and regulate the process. If the recipient is unavailable (for example, when the mobile phone is switched off), the SMSC will store the SMS message. It will forward the SMS message when the recipient is available.
Very often an SMSC is dedicated to handle the SMS traffic of one wireless network. A network operator usually manages its own SMSC(s) and locates them inside its wireless network system. However, it is possible for a network operator to use a third-party SMSC that is located outside the wireless network system.
You must know the address of the wireless network operator's SMSC in order to use SMS messaging with your mobile phone. Typically an SMSC address is an ordinary phone number in the international format. A mobile phone should have a menu option that can be used to configure the SMSC address. Normally, the SMSC address is pre-set in the SIM card by the wireless network operator, which means you do not need to make any changes to it.
Inter-operator SMS Messages (Contd)
he first way can be used if the two wireless networks involved in the transmission of the inter-operator SMS message are based on similar technologies. However, if this is not true, the second way has to be used. For example, when an SMS message is sent from a GSM network to a CDMA network. In the second way, the originator SMS center and the recipient SMS center are interconnected through an SMS gateway or with a communication protocol that is supported by both SMS centers. The SMS message first reaches the originator SMS center, which will then forward the SMS message towards the recipient SMS center. The recipient SMS center will be responsible for sending the SMS message to the recipient mobile phone and storing the SMS message if the recipient mobile phone is offline. The following figure illustrates the transmission process:
Inter-operator SMS Messages
Suppose you and your friend are using the mobile phone service of wireless network operator A and wireless network operator B respectively. The transmission of an SMS message from you to your friend involves two wireless networks. This SMS message is called an inter-operator SMS message.Typically, the cost for sending an inter-operator SMS message from a mobile phone is higher than that for sending an intra-operator SMS message.
Transmission Process of Inter-operator SMS Messages
The transmission of an inter-operator SMS message involves one or more SMS centers. Generally, there are two different ways for the transmission of inter-operator SMS messages. In the first way, signaling interconnections are set up between two wireless networks. When the originator SMS center receives an inter-operator SMS message, it gets the routing information from the recipient wireless network and delivers the SMS message to the recipient mobile phone directly. The following figure illustrates the transmission process:
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