Q:

Send and receive SMSs to a PHP script? 

Can a PHP script (which can be working with a MySQL DB) send and/or receive SMSs using some sort of server-side solution? 
Any special server-side application, or special hardware required? 
And compatibility?  Windows, Linux? 

A:

There are plenty of companies like Esendex that offer APIs for sending/receiving SMS messages.   I'm not sure if you're looking to send them directly from your hardware though?