How to Send SMS Messages from a Computer / PC?
In 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.
If you do not want to develop SMS software or applications but just want to use your computer / PC to send text messages, you may want to read our Quick Guide for Non-Developers.
10.1. 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
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.
10.1.1. Major Drawback of Sending SMS Messages through a Mobile Phone or GSM/GPRS Modem -- Low SMS Sending Rate
Using a mobile phone or GSM/GPRS modem to send SMS messages has a major drawback, that is the SMS sending rate is too low. Only 6-10 SMS messages can be sent per minute (when the "SMS over GSM" mode is used). The performance is not affected by the connection between the computer and the mobile phone or GSM/GPRS modem (i.e. the SMS sending rate is about the same no matter the mobile phone or GSM/GPRS modem is connected to the computer through a serial cable, USB cable, Bluetooth link or infrared link) and does not depend on whether a mobile phone or GSM/GPRS modem is used (i.e. the SMS sending rate is about the same no matter a mobile phone or a GSM/GPRS modem is used). The determining factor for the SMS sending rate is the wireless network.
Wednesday, March 11, 2009
Sunday, March 8, 2009
Send SMS Through SMS Gateway- Cheapest ways to Send SMS Part 2
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.
Figure 1. An SMS gateway acts as a relay between two SMS centers.
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.
Figure 2. An SMS text messaging application connects to SMSCs without an SMS gateway.
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.
Figure 3. An SMS text messaging application connects to SMSCs through an SMS gateway.
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.
Figure 4. An SMS text messaging application connects to a pool of mobile phones or GSM/GPRS modems through an SMS gateway.
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/
Figure 1. An SMS gateway acts as a relay between two SMS centers.
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.
Figure 2. An SMS text messaging application connects to SMSCs without an SMS gateway.
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.
Figure 3. An SMS text messaging application connects to SMSCs through an SMS gateway.
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.
Figure 4. An SMS text messaging application connects to a pool of mobile phones or GSM/GPRS modems through an SMS gateway.
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/
Wednesday, March 4, 2009
Send SMS Through SMS Gateway- Cheapest ways to Send SMS
There is a demand for SMS connectivity from applications that does not require the sending or receiving of large amount of SMS messages. One example is a remote monitoring system. If the remote monitoring system finds that a certain server is not responding, it will send an SMS alert to the system administrator's mobile phone. This remote monitoring system will have a very small amount of SMS traffic per month since the servers being monitored should be working fine most of the time.
Since a wireless carrier usually does not provide direct SMSC or SMS gateway access to users without a large amount of SMS traffic, some companies come out to fill the gap. These companies are called SMS service providers. There is no minimal purchase requirement or monthly minimum usage requirement for many SMS service providers.
SMS service providers are also known as SMS gateway providers, SMS resellers and SMS brokers because of the following reasons:
SMS gateway providers -- An SMS service provider provides an SMS gateway for its users to send SMS messages to. This SMS gateway will then route the SMS messages to another SMS gateway or SMSC.
SMS resellers and SMS brokers -- SMS service providers buy a large amount of SMS messages from a lot of wireless carriers at a low price per SMS message. They then sell the SMS messages at a price higher than the cost.
Unlike wireless carriers, many SMS service providers provide detail information about their SMS connectivity service on their web site. For example, you may find the cost of the service, network coverage, protocols supported, developers' guide, etc, on the web site. Thus, the service of different SMS service providers can be compared easily. If you are not happy with, say the price or network coverage of an SMS service provider, you can simply leave its web site and find another SMS service provider.
Another advantage of using the SMS connectivity services of SMS service providers is that their network coverage is very good. They work hard to cover as many wireless networks as possible so as to make their services attractive. Some SMS service providers can send SMS messages not only to GSM wireless networks, but also to CDMA and TDMA wireless networks.
It is easy to send SMS messages with an SMS service provider. Here are the typical steps:
Register for an account on the SMS service provider's web site. (An SMS service provider may allow newly registered users to send a few free SMS messages for testing its service quality.)
Log into the account.
Buy a number of credits or SMS text messages online. Many SMS service providers support credit card payment and some also support PayPal.
Send SMS messages using a protocol / interface (e.g. HTTP, email, FTP) supported by the SMS service provider.
SMS service providers can be divided into two categories depending on how they require you to pay for their SMS messaging service:
Credit-based -- You purchase a number of credits from the SMS service provider's web site. Sending one SMS message will cost you one or more credits, depending on the country you send the SMS message to. For example, sending an SMS text message to India might cost you one credit while sending an SMS text message to the US might cost you two credits.
SMS-based -- You purchase a number of SMS messages from the SMS service provider's web site. The cost per SMS message is the same for all destinations. For example, if you purchase ten SMS messages, you can send at most ten SMS messages no matter the destination is India or the US.
The cost per SMS message sent depends on which SMS service provider you choose and how many SMS messages you purchase. It starts at around INR .10 to INR .50 per SMS message. The more SMS messages you purchased, the lower the cost of sending one SMS message.
Since a wireless carrier usually does not provide direct SMSC or SMS gateway access to users without a large amount of SMS traffic, some companies come out to fill the gap. These companies are called SMS service providers. There is no minimal purchase requirement or monthly minimum usage requirement for many SMS service providers.
SMS service providers are also known as SMS gateway providers, SMS resellers and SMS brokers because of the following reasons:
SMS gateway providers -- An SMS service provider provides an SMS gateway for its users to send SMS messages to. This SMS gateway will then route the SMS messages to another SMS gateway or SMSC.
SMS resellers and SMS brokers -- SMS service providers buy a large amount of SMS messages from a lot of wireless carriers at a low price per SMS message. They then sell the SMS messages at a price higher than the cost.
Unlike wireless carriers, many SMS service providers provide detail information about their SMS connectivity service on their web site. For example, you may find the cost of the service, network coverage, protocols supported, developers' guide, etc, on the web site. Thus, the service of different SMS service providers can be compared easily. If you are not happy with, say the price or network coverage of an SMS service provider, you can simply leave its web site and find another SMS service provider.
Another advantage of using the SMS connectivity services of SMS service providers is that their network coverage is very good. They work hard to cover as many wireless networks as possible so as to make their services attractive. Some SMS service providers can send SMS messages not only to GSM wireless networks, but also to CDMA and TDMA wireless networks.
It is easy to send SMS messages with an SMS service provider. Here are the typical steps:
Register for an account on the SMS service provider's web site. (An SMS service provider may allow newly registered users to send a few free SMS messages for testing its service quality.)
Log into the account.
Buy a number of credits or SMS text messages online. Many SMS service providers support credit card payment and some also support PayPal.
Send SMS messages using a protocol / interface (e.g. HTTP, email, FTP) supported by the SMS service provider.
SMS service providers can be divided into two categories depending on how they require you to pay for their SMS messaging service:
Credit-based -- You purchase a number of credits from the SMS service provider's web site. Sending one SMS message will cost you one or more credits, depending on the country you send the SMS message to. For example, sending an SMS text message to India might cost you one credit while sending an SMS text message to the US might cost you two credits.
SMS-based -- You purchase a number of SMS messages from the SMS service provider's web site. The cost per SMS message is the same for all destinations. For example, if you purchase ten SMS messages, you can send at most ten SMS messages no matter the destination is India or the US.
The cost per SMS message sent depends on which SMS service provider you choose and how many SMS messages you purchase. It starts at around INR .10 to INR .50 per SMS message. The more SMS messages you purchased, the lower the cost of sending one SMS message.
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