Since the invention of the Internet, a new era of convergence of technologies has ushered, bringing close distant technologies which could not have been thought to be related at all. Sure, we can send a mail from our GPRS activated cellular device, but is the reverse true? Can we send a text message from the Internet? The answer is yes and we all have used free online SMS sending websites either on a regular basis or just for testing if it works or is merely faking. The best and the most attractive part is the word ‘free’ and sometimes, ‘unlimited’ too. But have you ever wondered how this is made possible? We're going to cruise along the path an online SMS would follow in the whole process in the next few pages.
The first and foremost requirement is a terminal with an internet browser and internet access. We visit any website offering free SMS service, say www.xyz.com and register for a free account (Some websites allow sending SMS as guest users too). This would be sufficient on the end users part to get started. To send an online SMS, an interface is presented to the user which allows them to enter the destination mobile number and the Text Message. Usually, the service is offered on a national basis through an Aggregator Gateway adopting Local Termination model, i.e. we are allowed to send messages on numbers from the same country only, but a few premium sites may offer international messaging too.
The life of an online SMS commences in the network jungle the moment you click on the send button. And that is where the user can cross fingers and hope it reaches the intended recipient while waiting for a delivery report. The internet is a quagmire of various protocols which help us to navigate through the World Wide Web. One of the most common formats adopted is the HTTP (Hyper Text Transfer Protocol), which does an effective cross-linking and navigation of various nodes of the webspace. The message entered by the user may travel the web in various protocols like HTTP, HTTPS (HTTP + SSL encryption), XML over HTTP / HTTPS, SMTP (email to SMS), and FTP. A simple HTTP request can be like:
The block diagram of the message flow is shown above.