How to write sms with php?

[rich]

Short information (system:redhat+php)

[the_Igel]

You can't send sms directly from internet, 'cause it's not a web-service; you always need a gate.

Find a webform for sending sms, "sms-gate".
View the code to learn what data it sends and to what url.
Format a request in your script according to retrieved information.
Send it.
Here you are.

[mikesgt2]

Somone has already written a class, you can get it here:

http://www.k1m.com/scripts/sms_web_sender/

This uses the methods that the_Ingel mentions, you use different extensions of the class that use different services.