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I want to understand in very simple steps/language what happens under the hood when 

a) an sms is sent to a number like 40404

b) A web server receives an HTTP request with GET/POST parameters and executes an action.

i) What actually happens between a) and b).

ii) What open source libraries (not cloud APIs) are there for handling that transition.

I know that there are APIs (like Twilio) etc that do this for me...but i want to know at a very high level what exactly is going on so I can actually learn this stuff.

John Saunders
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algorithmicCoder
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1 Answers1

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At a very high level, there is another mobile receiver (like your phone) on the other end. It receives the message and hands it to a computer. That computer has some program that understands the request (depending on implementation etc.), and can do any action it wants. For instance, it can send off a http request to a web server.

j13r
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  • Thanks! Can you suggest good resources for learning how the "mobile receiver" ..."hands off the message to a computer" ...and how to build this in practice? – algorithmicCoder Mar 24 '12 at 16:04
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    Technically, you can interact with a GSM modem and use the AT commands to send messages. I'm biased (as an employee) but check out Twilio. When you have a number with us, the message comes in and we make a POST to a url you configure with all the message parameters. – CaseySoftware Mar 24 '12 at 16:58
  • Go through this post (http://stackoverflow.com/questions/6893562/send-sms-from-desktop-application/8034620#8034620) to understand how SMSs can be sent through applications using SMS gateways and what happens beneath the hood. Hope this helps. – Drona Mar 24 '12 at 17:33
  • @CaseySoftware Twilio was mentioned in the question, which was about how such systems work; perhaps as an employee you can comment on what hardware you use. – j13r Mar 24 '12 at 19:23
  • @j13r - I can't tell you because honestly, I don't know. Though I know that we have direct relationships with the carriers. It's really the only reliable way to make sure messages are sent/received. Even with the GSM modem solution, all it takes is the number being blocked and your operations are dead. – CaseySoftware Mar 25 '12 at 18:13