Very simple project with Asterisk and PHP
To do in php:
1- Have a call me icon on a web page
2- You asked and sent client phone number to call
To do in Asterisk:
3- You asked Asterisk to call that number and the number associated with the "icon call me"
You save the information like the phone numbers associate in mysql
Dial plan to limited call to be only in the same country
Limit the call to 15 minutes