Submitted by WaverlyAddison t3_yer3fh in explainlikeimfive
I use a cloud based scheduling software and I can tell it to text message a client an appointment reminder 24 hours before their appointment. How does the software actually send text messages?
Edited for clarity
My b - how does the texting part work?
Well, the long answer is that it's actually extremely complicated. Not really because the process is particularly difficult, but because the actual software implementations of these things run through so many layers these days. In principle, sending a text message works like this:
Both you and the recipient agree on a code, such that certain binary combination translate to certain letters. For instance, perhaps 00000100 means 'a'. How this code works is ultimately irrelevant, so long as both parties agree. And from there, it's as simple as taking a letter you put in, translate it to binary according to this code, send electrical signals that represent this binary code and then decode it on the other end to get out the letter again. You do that for every letter, and there you go: Text message. Essentially, it's just a fancier version of Morse code.
Now, how this actually works in reality is a lot more complex. In order to understand how sending text works, you need to know how the software you happen to use works. In order to understand that, you need to understand the framework it's built on. To understand that, you need to understand the operating system it runs on. And so on and so forth through understanding web sockets and protocols and the physical connections between servers and blablabla. But, ultimately, the basic idea behind it is as simple as encoding text in binary and decoding it on the other end.
I'm not sure if that really answers your question, as it still strikes me as very vague.
I think they mean using software on a PC to send SMS. "Text message" was used as the standard term for SMS in a number of countries.
They'll usually use a service like Amazon Web Services Simple Notification System, or Twilio. These allow you to send text messages using a web request just like how you load a web page. Then it is just a case of writing a piece of software to decide when to send the request and what to put into it.
Those services I mentioned will send the text message from a number or alphanumeric sender ID (where you see text messages from a sender who is a word or phrase rather than a phone number) into the network of the carrier that the recipients SIM card is registered with.
Twilio will even notify your software if the message gets rejected because it is considered spam, or the carrier doesn't support receiving messages from Twilio, or if they have their phone switched off and the message doesn't go through. It is pretty cool how it works and how easy it is to use!
this makes it sound like spamming texts would be easy? maybe the carrier can shut u down based on rules like—did u just send the same message to 100 different numbers? if so then block all ur future messages?
Twilio will also detect spam messages, but carriers do it as well, yeah.
If you're asking how a computer sends a text to a phone
The software is connected to a system that has an assigned phone number. When you send a message, the software handles it the same way your phone sends a text using it's assigned number. The recipients phone doesn't know (or care) how the message originated.
With everything being IP, there's not much difference between your smartphone and a "computer".
These days, the companies who run phone networks (telecommunication carriers, aka "telcos" or "carriers") run all their networks via computers. If you send an SMS from one phone to another, it's likely already passing through multiple computers, so they can do things like collect logs for billing, queue messages for later delivery in case one phone is out of service, transfer messages to recipients on other carrier networks (eg. send it overseas via internet) etc.
These carriers might also provide a service that allows third parties to send SMS without using a phone, or connected to their cell network. Basically, one computer sends data to another computer run by the carrier - an SMS gateway - that will create the SMS message and push it out to the recipient phones. This generally costs money to use.
Some SMS gateways are used via web requests - like a REST API that many websites use today - others work by converting specific emails to SMS (eg. send an email to 123456789@sms.xyzcarrier.com, and the email body will be the text message).
There are also online services that act as a middleman, also confusingly calling themselves SMS Gateways. They deal with the various carriers across the world and their different gateways, figuring out which carrier to use based on the country and phone number, while providing a single unified service for end users and programmers to use with a simplified billing plan. This is likely what your cloud software is using on the server-side code.
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They use a texting service provider such as Bandwidth. Bandwidth is basically a mobile carrier without towers and other cellular networking hardware. But they connect to other carriers exactly the same way a real mobile carrier does.
Nagransham t1_itzdrgl wrote
It's not entirely clear what technology you are actually asking about. The texting? Cloud services? Scheduling? Because depending on the depth of the question, the answers can go from very complex to "It's a timer", so some more detail would be helpful.