Short Message Service
Short Message Service, or shortly SMS, is a text messaging service component of cellphones,
web or mobile communication systems, using standardized communications protocols that
allow the exchange of short text messages (SMS) between fixed line or mobile phone devices.
Simply said, it is a method of communication that sends text messages between cell phones or
The "short" part refers to the maximum size of the text messages: including spaces, standard text messages
traditionally cannot exceed 160 characters (letters, numbers or symbols in the Latin alphabet).
For other alphabets, such as Chinese, the maximum SMS size is 70 characters.
Short Message Service provides the most widely used communication form in the world. Millions of
active users send messages daily containing personal information, content of business, market,
sales or news.
How it works?
When an SMS message is sent from a mobile phone, it will reach an SMS Center (SMSC) first. The
SMSC is responsible for handling and storing the SMS operations of a wireless network. After its arrival, the
SMSC forwards the SMS message towards the recipient.
The SMSC does this by sending an SMS Request
to the home location register (HLR) to find the recipient. After receiving the request, the HLR
sends back the recipient's status to the SMSC. The status can be active or inactive and it also
includes the location where the recipient is roaming. If the response is "inactive", the SMSC
holds back the message. If the HLR finds access to the target device a notification is sent to
the SMSC and the delivery occurs.
When a message is received by the recipient the SMSC categorizes
it as "sent" and delivers it no more. 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.
SMS sending from a computer
As it is widely known SMS messages can be sent from cell phones. However, when you need
to send out a larger number of SMS messages it is highly recommend to send them from PC.
For sending messages from PC you need to introduce an SMS gateway software.
SMS sending from a PC can be performed two ways: You can setup a wireless connection with a GSM modem or an IP SMS
connection. Both connection types have advantages and disadvantages.
SMS gateway providers
- A wireless connection can be used to send/receive SMS messages if you attach a GSM modem (or GSM phone)
to your PC with a phone to PC data cable. The GSM Modem has a SIM card that makes it possible to
attach to the GSM network. The major advantage of this connection is that it can be easily set up.
You can simply purchase a SIM card and a GSM modem and youíre ready to get the system up quickly.
The operational costs of this method are low. You can purchase a prepaid SIM which doesnít have a
monthly fee. The drawback of this connection type is its relative slowness. You can only transmit/receive
about 10 messages per minute. (This capacity can be increased by using more GSM modems.) If you want
to create an SMS service that will not send/receive a very large amount of messages, this is an
- Another option is to connect your system directly to the short message service center of a
GSM service provider over the Internet. In this case you have a significantly better bandwidth
(max. 10 000 SMS/ minute), but you usually have to pay a large monthly fee and it takes a lot
of time and is hard to sign a contract with a service provider. IP SMS connections use IP SMS
protocols: SMPP or CIMD2 or UCP/EMI.
If you donít feel necessary to connect to the mobile network directly, you can choose to buy
some services from an SMS gateway provider. This way you will pay for a formerly defined amount
of SMS messages that you can send out then. Typically, SMS gateway providers can be
divided into 2 categories in terms of how they require you to pay for their SMS service:
You purchase a number of credits from the SMS gateway provider. Sending one SMS message
will cost you one or more credits, depending on the country you send the SMS message to.
(e.g. sending an SMS to India might cost you one credit while sending an SMS to the
USA might cost you two credits)
You purchase a number of SMS messages from the SMS gateway provider. The cost for
sending one SMS message is the same for all destinations.
A few SMS gateway providers offer a very low price per SMS message, but their network
quality is poor and an SMS message may not reach its destination, or it may only reach
the destination after a long delay.
SMS messaging services can be grouped into two categories: 1-way and 2-way. 1-way SMS
messaging services allow you to send SMS messages, while 2-way SMS
allow you to send and receive SMS messages. All SMS gateway providers provide 1-way SMS
messaging services but only some of them provide 2-way SMS messaging services, because
it is technically more difficult for an SMS gateway provider to enable its users to receive
SMS messages than to send SMS messages.
To get more information, please visit the following websites:
The Ozeki NG SMS Gateway website
The best site about SMS integration