In general, there are three ways to receive SMS messages using your computer / PC:
Connect a mobile phone or GSM/GPRS modem to a computer / PC. Then use the computer / PC and AT commands to get the received SMS messages from the mobile phone or GSM/GPRS modem.
Get access to the SMS center (SMSC) or SMS gateway of a wireless carrier. Any SMS messages received will be forwarded to your computer / PC using a protocol / interface supported by the SMSC or SMS gateway.
Get access to the SMS gateway of an SMS service provider. Any SMS messages received will be forwarded to your computer / PC using a protocol / interface supported by the SMS gateway.
If you do not want to develop SMS software or applications but just want to use your computer / PC to receive text messages, you may want to read our Quick Guide for Non-Developers.
1. The 1st Way: Using a Computer to Receive SMS Messages through a Mobile Phone or GSM/GPRS Modem
Receiving SMS messages through a mobile phone or GSM/GPRS modem has a major advantage over the other two ways -- wireless carriers usually do not charge any fees for receiving incoming SMS messages with their SIM cards. The disadvantage of receiving SMS messages this way is that a mobile phone or GSM/GPRS modem cannot handle a large amount of SMS traffic. One way to overcome this is to load balance the SMS traffic with a pool of mobile phones or GSM/GPRS modems. Each mobile phone or GSM/GPRS modem will have its own SIM card and mobile phone number.
In terms of programming, sending and receiving SMS messages through a mobile phone or GSM/GPRS modem are similar. What you need to do is to send instructions (in the form of AT commands) to the mobile phone or GSM/GPRS modem.
The following table lists the AT commands that are related to the receiving and reading of SMS messages:
| AT command | Meaning |
|---|---|
| +CNMI | New message indications |
| +CMGL | List messages |
| +CMGR | Read messages |
| +CNMA | New message acknowledgement |
Below shows a simple example that demonstrates how to use AT commands and the HyperTerminal program of Microsoft Windows to read SMS text messages received by a GSM / GPRS modem or mobile phone. 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+CMGL="ALL"
+CMGL: 1,"REC READ","+85291234567",,"06/11/11,00:30:29+32"
Hello, welcome to our SMS tutorial.
+CMGL: 2,"REC READ","+85291234567",,"06/11/11,00:32:20+32"
A simple demo of SMS text messaging.
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 5-9: The AT command +CMGL is used to list all SMS text messages in the message storage of the GSM / GPRS modem. There are two SMS text messages in the message storage: "Hello, welcome to our SMS tutorial." and "A simple demo of SMS text messaging.". "+85291234567" is the sender mobile phone number. "06/11/11,00:30:29+32" and "06/11/11,00:32:20+32" tell us when the SMS text messages were received by the SMSC. "+32" is the time zone. Note that the unit is a quarter of an hour. So, +32 means GMT+8 hours, since 32 quarters of an hour = 8 hours. "REC READ" indicates both of the SMS text messages have been read before.
Line 11: The result code "OK" indicates the execution of the AT command +CMGL is successful.
To enable an application to receive SMS messages, 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 (such as HyperTerminal of Microsoft Windows) does. You can write the source code in C, C++, Java, Visual Basic, Delphi or other programming languages you like.
However, like what we have discussed in the earlier section "The 1st Way: Sending SMS Messages from a Computer Using a Mobile Phone or GSM/GPRS Modem", usually a better solution is to use a high-level SMS messaging API (Application programming interface) / SDK (Software development kit) / library instead of writing your own code for interacting with the mobile phone or GSM/GPRS modem via AT commands. 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 high-level solution is to place an SMS gateway between the SMS messaging application and the mobile phone or GSM/GPRS modem. The SMS messaging application can then use simple protocols such as HTTP / HTTPS for receiving SMS messages. 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.
2. The 2nd Way: Using a Computer to Receive SMS Messages through a Connection to the SMSC or SMS Gateway of a Wireless Carrier
Like sending SMS messages, receiving SMS messages through a mobile phone or GSM/GPRS modem has a major limitation, that is the SMS transmission rate is too low. If you need a high SMS transmission rate, one way is to obtain a direct connection to the SMS center (SMSC) or SMS gateway of a wireless carrier. The connection may be made through the Internet, X.25 or dial-up.
To receive SMS messages through a direct connection to the SMSC or SMS gateway of a wireless carrier, usually you need to contact the wireless carrier staff to discuss the details. A wireless carrier may only provide such service to those who have huge SMS traffic and the total fee can be very high. (However, if you divide the total fee by the number of SMS messages that is allowed to receive through the SMSC or SMS gateway, you may find that the fee per incoming SMS message is very low.) The service may involve a one-time setup fee, a monthly subscription fee and/or a per-message fee. To know the exact cost of the service, protocols supported, network coverage and other information, usually you have to contact the wireless carrier staff.
3. The 3rd Way: Using a Computer to Receive SMS Messages through a Connection to the SMS Gateway of an SMS Service Provider
Another way to receive SMS messages using a computer is through a connection to the SMS gateway of an SMS service provider. SMS service providers generally support two kinds of solution:
SIM hosting -- The SMS service provider hosts a SIM card for you. All SMS messages sent to the mobile phone number of the SIM card will be forwarded to your system using a protocol / interface supported by the SMS gateway of the SMS service provider.
Shared phone number -- The SMS service provider provides you a phone number that is shared by its customers for receiving SMS messages. You have to specify one or more keywords to associate with your SMS application. If an SMS message is received and its content begins with a keyword specified by you, it will be forwarded to your system using a protocol / interface supported by the SMS gateway of the SMS service provider.
Some SMS service providers also provide SMS messaging solutions that are customized to your needs. For example, if you need to receive SMS messages from users in a few countries, an SMS service provider may help you open dedicated phone numbers in those countries and forward the received SMS messages to you in a unified way. To use such SMS messaging services, you have to contact the SMS service provider to discuss the details.
3.1. SIM Hosting
In this approach, an SMS service provider hosts a SIM card for you. The SIM card's mobile phone number will serve as a dedicated phone number of your SMS application. To use the service, you mail your SIM card to the SMS service provider. Later if you end the service, the SMS service provider will mail the SIM card back to you. The SIM card will be put into a GSM/GPRS modem, which is connected to an SMS gateway. The SMS gateway will forward all received SMS messages to your computer using a certain protocol / interface. For example, HTTP, HTTPS, XML over HTTP/HTTPS, SMTP (SMS to email), SMPP, etc.
Like receiving SMS messages using your own mobile phone or GSM/GPRS modem, SIM hosting has a major weakness -- it cannot handle a large amount of SMS traffic. The advantage of SIM hosting is that you do not need to buy, set up and manage the necessary equipment. Also, you do not need to write any code to control the receiving of SMS messages from a GSM/GPRS modem via low-level AT commands, which means you can concentrate on the business logic of your SMS application. The SMS service provider may provide you a detail log of the incoming SMS messages.
3.1.1. Cost of SIM Hosting Service
SIM hosting service typically involves a one-time setup fee and a monthly hosting fee. Usually there is no per-message cost. Some SMS service providers do not state the cost of SIM hosting service on their website, which means you have to contact their staff directly.
If the SMS service provider is located overseas, the SIM card needs to support foreign network roaming. SMS roaming fees may be charged by the wireless carrier that provides you the SIM card.
3.2. Shared Phone Number
In this approach, the SMS service provider rents dedicated phone numbers from wireless carriers. Each phone number will then be shared by a number of the SMS service provider's customers for receiving SMS messages. Since the phone number is provided by a wireless carrier directly (not through a SIM card) and the SMS service provider has a high speed connection to the SMSC or SMS gateway of the wireless carrier, the SMS service provider is capable of handling a large amount of SMS messages with the phone number. As a result, the users of such shared phone number service can enjoy a higher SMS transmission rate than using SIM hosting services or using their own wireless modem. The cost of shared phone number service is less expensive than renting your own dedicated phone number from a wireless carrier. A detail log of the received SMS messages is sometimes provided by SMS service providers.
Like using SIM hosting service, using shared phone number service has the advantage that you do not need to buy, set up and manage any equipment (e.g. GSM / GPRS modems) and write any low-level code for receiving SMS messages. Hence, an SMS application developer can concentrate on the business logic of his/her SMS messaging application.
The weakness of shared phone number service is that the bandwidth is shared, i.e. the performance drops if the number of users sharing the phone number increases, or if the amount of incoming SMS traffic required by other users increases.
3.2.1. Registering Keywords
Since multiple users share a single phone number, when the SMS gateway of the SMS service provider receives an SMS message, it needs a way to determine which user to forward the SMS message to. SMS service providers' engineers come up with a solution like this: First, a user registers one or more keywords to associate with his/her SMS messaging application. Later when the SMS gateway receives an SMS message that begins with one of the keywords, it will forward the SMS message to that SMS messaging application.
Here is an example for illustration. Suppose you want to develop an SMS messaging application that provides free ringtone download service. A user will be able to perform two functions: listing the free ringtones that are available and requesting a ringtone to be sent to a mobile phone.
To receive SMS messages from users, you can subscribe to the shared phone number service of an SMS service provider and register two keywords, list and download, to be associated with your SMS messaging application.
To request the list of free ringtones that are available on your server, the user can send the following SMS text message to the shared phone number:
list
When the SMS gateway of the SMS service provider receives the above SMS text message, it parses its content and extracts the keyword list. It then searches a database to find out which SMS messaging application is associated with the keyword list. As your SMS messaging application is associated with the keyword list, the SMS text message will be forwarded to your SMS messaging application.
The keyword list indicates that the user wants the list of free ringtones that are available on your server. Hence, your SMS messaging application should return an SMS text message that contains something like this:
Free ringtones available:
1. Ringtone ABC
2. Ringtone CDEF
3. Ringtone X
4. Ringtone Y
To download the second ringtone, the user can send an SMS text message that looks like this to the shared phone number:
download 2
Since the keyword download is also associated with your SMS messaging application, the SMS gateway will forward the above SMS text message to your SMS messaging application. This time the keyword download indicates that the user wants to download a ringtone. Your SMS messaging application should encode the second ringtone in an SMS message and send it to the user.
3.2.2. Cost of Shared Phone Number Service
Shared phone number service typically involves a monthly subscription fee, a per-message fee and/or a per-keyword fee. A few SMS service providers also charge a one-time setup fee. Some SMS service providers do not state the cost of shared phone number service on their web site, which means you have to contact their staff directly.
4. Receiving SMS Messages Using a Protocol / Interface Supported by an SMSC or SMS Gateway
After setting up an account with a wireless carrier or an SMS service provider, the SMSC or SMS gateway will start forwarding inbound SMS messages to your SMS application using a certain a protocol / interface. To communicate with an SMSC, an SMSC protocol is required. As mentioned in earlier sections of this SMS tutorial, most of these SMSC protocols are proprietary to the company that developed the SMSC. One widely used SMSC protocol is SMPP (Short Message Peer to Peer). It was originally a proprietary SMSC protocol created by Logica (an SMSC vendor). Now SMPP is an open SMSC protocol whose development is controlled by a non-profit organization SMS Forum. The following table lists some of the SMSC protocols and the SMSC vendors who develop the protocols:
| SMSC vendor | SMSC protocol |
|---|---|
| CMG (CMG and Logica have merged into LogicaCMG.) | EMI (External Machine Interface) UCP (Universal Computer Protocol) |
| Logica (CMG and Logica have merged into LogicaCMG.) (Now the SMS Forum is responsible for the development of SMPP.) | SMPP (Short Message Peer to Peer) |
| CIMD (Computer Interface to Message Distribution) | |
| SEMA Group (Now Airwide Solutions) | OIS (Open Interface Specification) SMS2000 |
SMS gateways of SMS service providers and wireless carriers very often support one or more of the following protocols / interfaces: HTTP, HTTPS (HTTP + SSL encryption), XML over HTTP / HTTPS, SMTP (SMS to email), FTP. Some also support the SMPP protocol, which is usually used by advanced users. SMSC protocols other than SMPP are not commonly supported.
It is very easy to receive SMS messages from an SMS gateway if you use a simple protocol like HTTP / HTTPS. Let's take HTTP as an example. First, you log into your account and register a callback URL that points to a server-side script written by you. The server-side script is hosted on a web server / application server and it will be responsible for processing the received SMS messages. Commonly used server-side technologies include ASP, Java Servlet / JSP, Perl and PHP. If your server-side script is written in PHP, the callback URL should look something like this:
http://yourserver.com/receiveSMS.php
Whenever an SMS message is received, the SMS gateway will submit an HTTP GET to your web server / application server using the above callback URL. Details of the inbound SMS message such as its content, the sender's mobile phone number, the time and date that the SMS message is received, etc, will be appended to the callback URL. For example, suppose someone with the mobile phone number 61234567 sends an SMS text message "It is easy to receive text messages" to your SMS application's phone number. When the SMS gateway receives the SMS text message, it submits an HTTP GET to your web server / application server using an URL that looks like this:
http://yourserver.com/receiveSMS.php?sender=61234567&textmessage=It+is+easy+to+receive+text+messages&date_time=20060101+1830
In the above URL:
"yourserver.com" is the host name of your web server / application server that is responsible for processing the inbound SMS text message.
"receiveSMS.php" is the file that contains the PHP script for processing the inbound SMS text message.
"sender=61234567" assigns the value 61234567 to the sender parameter. The sender parameter specifies the originating mobile phone number.
"textmessage=It+is+easy+to+receive+text+messages" assigns the value It is easy to receive text messages to the textmessage parameter. The textmessage parameter specifies the content of the inbound SMS text message. The "+" character is the escaped character of the space character. The space character is a special character and it cannot appear in an URL without escaping.
"date_time=20060101+1830" assigns the value 20060101 1830 to the date_time parameter. The date_time parameter specifies the date and time that the SMS text message was received. In this example, 20060101 1830 means the SMS text message was received on 1 January 2006 at 6:30 pm. The date and time format may be different if you use the SMS gateway of a different SMS service provider or wireless carrier.
After processing the inbound SMS text message, you may want to send a reply SMS text message to the originator. Usually this can be done simply by including the reply SMS text message in the HTTP response you send back to the SMS gateway. The SMS gateway will then forward the included text message towards the mobile phone number 61234567. The cost for sending the SMS text message will be deducted from your account.
Note that the parameters that are included in the callback URL varies between SMS gateways of different SMS service providers or wireless carriers. For example, if a different SMS gateway is used, the previous SMS message "It is easy to receive text messages" may be forwarded to your web server / application server using a different URL, like below:
http://yourserver.com/receiveSMS.php?from=61234567&msg=It+is+easy+to+receive+text+messages×tamp=1830+01012006
Also, note that data transmitted over the Internet using the HTTP protocol is not secure. This means other people can read the data included in the above URL. Some SMS gateways allow the use of the HTTPS protocol instead of HTTP in a callback URL (i.e. change "http" at the beginning of the above URL to "https") so that inbound SMS messages can be submitted to your web server / application server securely. (HTTPS must be enabled on your web server / application server.)
https://yourserver.com/receiveSMS.php?from=61234567&msg=It+is+easy+to+receive+text+messages×tamp=1830+01012006
Source Article : http://www.developershome.com/sms/
