How to create web sms sender
First install a web server
I choose lighttpd (make menuconfig ->Package selection for the target ). Select Show package that are also provide by busybox and lighttpd.
We also need php support (Interpreter language and scripting). Enable php and fastcgi, active also PCRE extenstion.
Second adapt exemple script for sending sms. This is mine  (I still have to improve it so if you have comments)
Third create web pages a basic formular and a php treatement page or all in one. Dont forget that we have to send smsm in GSM 03.38 so I have made my small convert function .