How to send sms programmatically? [closed]

Are there any sites that offer the ability to send SMS for free?

How do they do it?

How am I able to send SMS programmatically?

Solution 1:

The articles listed below may be useful:
Are there any free services for sending SMS programmatically?
[Programmatic SMS] [3]
[Free SMS API?] [4]

EDIT Removed first link that has been removed

Send an email to the 10 digit phone number @ Carrier's domain name.

Here is a list of the carriers and their domains:

https://en.wikipedia.org/wiki/List_of_SMS_gateways