sms through php from any no

I know I can send sms through php using api or gateway. But my question is how those websites send sms through our mobile no. How is this done开发者_如何学编程. Any help

---

SMS is fundamentally like email, it trusts the sender to be truthful about who they are sending from. I use clickatell to send SMS and in the early days - 2004/5 you could send an sms to anyone from anyone without any special permission, but they quickly shut this down for security reasons, you now have to register and prove your rights to send from a particular address.

Basically in order for you to do it you need to either sign up with a mobile provider or have an agreement with your sms provider to allow you to send sms from whoever you wish. There may be senders out there who are less strict in setting the sender.

---

They would communicate with a provider (possibly through a third party) also using an API of sort. One of the parameters they would pass is a source number. So when the SMS is sent there is header information saying it came from a specific number. It is possible to set this value to a text string too instead of a number. So the SMS might look to come from for example 'STACKOVERFLOW' instead of '12345678'.