How do websites like facebook send SMS alerts?

[T.J. Aston]

I'm curious how they send out notifications via SMS when something gets updated. Do they e-mail the message to your service providers phone address (aka numberhere@provider.dom)? Or is there some other trick they use?

[Max]

SMS alerts are for notifications & protection of your account. It helps in recovering your account (in case you forget password) and prevents your account from being hacked

Sites like Facebook, Google, etc have contracts with service provider. Just like banks send alert when you swipe debit/credit card or courier companies send you alert when package is shipped

Service provider only tracks number of SMS sent/received. They usually don't read them, unless it's really necessary