Description

Short Message Service (SMS) is the text communication service component of phone, web or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices. SMS text messaging is the most widely used data application in the world, with 2.4 billion active users, or 74% of all mobile phone subscribers.[citation needed] The term SMS is used as a synonym for all types of short text messaging, as well as the user activity itself, in many parts of the world.

As suggested by the name “Short Message Service”, the data that can be held by an SMS message is very limited. One SMS message can contain at most 140 bytes (1120 bits) of data, so one SMS message can contain up to:

160 characters if 7-bit character encoding is used. (7-bit character encoding is suitable for encoding Latin characters like English alphabets.)

70 characters if 16-bit Unicode UCS2 character encoding is used. (SMS text messages containing non-Latin characters like Chinese characters should use 16-bit character encoding.)

SMS text messaging supports languages internationally. It works fine with all languages supported by Unicode, including Arabic, Chinese, Japanese and Korean.

Besides text, SMS messages can also carry binary data. It is possible to send ringtones, pictures, operator logos, wallpapers, animations, business cards (e.g. VCards) and WAP configurations to a mobile phone with SMS messages.

One major advantage of SMS is that it is supported by 100% GSM mobile phones. Almost all subscription plans provided by wireless carriers include inexpensive SMS messaging service. Unlike SMS, mobile technologies such as WAP and mobile Java are not supported on many old mobile phone models.

One drawback of the SMS technology is that one SMS message can only carry a very limited amount of data. To overcome this drawback, an extension called concatenated SMS (also known as long SMS) was developed. A concatenated SMS text message can contain more than 160 English characters. Concatenated SMS works like this: The sender’s mobile phone breaks down a long message into smaller parts and sends each of them as a single SMS message. When these SMS messages reach the destination, the recipient mobile phone will combine them back to one long message.

The drawback of concatenated SMS is that it is less widely supported than SMS on wireless devices.

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.

Following are the ways to send SMS messages from a computer / PC to a mobile phone:

DIRECT GSM MODEM

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. You can use following AT commands to directly communicate with Modem.

AT command
+CMGS - Send message
+CMSS - Send message from storage
+CMGW - Write message to memory
+CMGD - Delete message
+CMGC - Send command
+CMMS More messages to send

FROM COMPUTER WITHOUT MODEM
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 can use a website like http://www.baapkamaal.com to register online and send free messages from computer. You can use PHP Curl utility to connect to any bulk SMS gateway and send text message

EMAIL2SMS

For this you need to have a fetchmail kind of service running which can authenticate based on subject line further passing it to SMS api.

Messaging Support matrix

Mobile network Standard Type SMS Availability Message Length Deployment
GSM 900 Digital Yes 160 Widely
GSM 1800 Digital Yes 160 Widely
GSM 1900 Digital Yes 160 Widely
TACS/ETACS Analog No N/A N/A
NMT Analog Yes N/A Eastern Europe
TDMA/D-AMPS Digital Yes N/A North America
NAMPS Analog Yes 14 alphanumeric
32 numeric North America
CDMA Digital Yes 256 North America
PHS Digital Yes N/A Japan
PDC Digital Yes N/A Japan
IDEN/NEXTEL Digital Yes 140 North and South America
TETRA/ Dolphin Digital Yes 256 Parts of Europe
Globalstar Satellite Yes 160 Truly global

Security Weaknesses of SMS is that SMS is vulnerable to DoS (Denial of Service) and identity spoofing attacks.

Abhishek Jain
Partner & Founder – BaapKaMaal
http://www.baapkamaal.com