Recently I've discovered Linphone which offers iOS SDK for creating VoIP calls. I would like to integrate it into my existing chat application and problem is that I need to make SIP service on my server which gives me a headaches. Is there any out of the box solution for this service which can be easily compiled and integrated with MySql database? I found OpenSIPS, Kamailio and Asterisk but since I'm new in this field they look very complicated at first. When you start Linphone example app you can create SIP user account using their free SIP service. I need to create similar service which can be used withing PHP script.
I have experience in UNIX / Linux and with server side programming (PHP & MySql) so even pointing me to a good tutorial would be very helpful.